Src homology 2 (SH2) domain found in the Cbl-b TKB domain; SH2 found in the Cbl-b TKB domain. The Cbl (for Casitas B-lineage lymphoma) family of E3 ubiquitin ligases contains three members Cbl, Cbl-b and Cbl-c. The founding member Cbl was discovered first as the oncogenic protein v-Cbl, a Gag-fusion transforming protein of Cas NS-1 retrovirus, which causes pre- and pro-B lymphomas in mice. The N-terminus of the Cbl proteins is composed of a tyrosine kinase-binding (TKB) domain, also called phosphotyrosine binding (PTB) domain, a short linker region and the RING-type zinc finger. In addition, Cbl and Cbl-b contain a leucine zipper motif and a proline-rich domain in the C-terminus. The TKB domain consists of a four-helix bundle (4H), a calcium-binding EF hand and a divergent SH2 domain. Cbl-b plays a role in early hematopoietic development and is a negative regulator of T-cell receptor, B-cell receptor and high affinity immunoglobulin epsilon receptor signal transduction pathways. It also negatively regulates insulin-like growth factor 1 signaling during muscle atrophy caused by unloading and is involved in EGFR ubiquitination and internalization. Diseases associated with defects in Cbl-b include: multiple sclerosis, autoimmune diseases, including type 1 diabetes, and a craniofacial phenotype. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313 222 KNWTYLAVTHPGYMAFLTYDEVKARLQAYVNKPGSYIFRLSCTRLGQWAIGYVTADGDILQTIPQNKSLFQALVDGQKEG 301
Cdd:cd09920     1 RNWQVLAVTHPGYMAFLTYDEVKARLQKFRDKPGSYVFRLSCTRLGQWAIGYVTADGKILQTIPQNKSLCQALIDGSREG 80

                          90
                  ....*....|....
gi 1974206313 302 FYLYPDGKNVNPDL 315
Cdd:cd09920    81 FYLYPDGRLDNPDL 94

CBL proto-oncogene N-terminus, EF hand-like domain; Cbl is an adaptor protein that binds EGF receptors (or other tyrosine kinases) and SH3 domains, functioning as a negative regulator of many signaling pathways. The N-terminal domain is evolutionarily conserved, and is known to bind to phosphorylated tyrosine residues. The so called N-terminal domain is actually 3 structural domains, of which this is the central EF hand domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313 145 YQLSKQEAQVFWRCTWRERSLVPWSEFQKGLQQVHPVDSGPMAIALKSTIDLTCSGHISIFEFDIFTRLFQPWPTLLKNW 224
Cdd:pfam02761   1 FRITKSEAAEFWKKSFGKRTIVPWKEFRTALQQVHGIESGLEAMALKSTIDLTCNDHISIFEFDVFTRLFQPWSTLLRNW 80

                  ....
gi 1974206313 225 TYLA 228
Cdd:pfam02761  81 NLLA 84

Src homology 2 (SH2) domain found in the Cbl-b TKB domain; SH2 found in the Cbl-b TKB domain. The Cbl (for Casitas B-lineage lymphoma) family of E3 ubiquitin ligases contains three members Cbl, Cbl-b and Cbl-c. The founding member Cbl was discovered first as the oncogenic protein v-Cbl, a Gag-fusion transforming protein of Cas NS-1 retrovirus, which causes pre- and pro-B lymphomas in mice. The N-terminus of the Cbl proteins is composed of a tyrosine kinase-binding (TKB) domain, also called phosphotyrosine binding (PTB) domain, a short linker region and the RING-type zinc finger. In addition, Cbl and Cbl-b contain a leucine zipper motif and a proline-rich domain in the C-terminus. The TKB domain consists of a four-helix bundle (4H), a calcium-binding EF hand and a divergent SH2 domain. Cbl-b plays a role in early hematopoietic development and is a negative regulator of T-cell receptor, B-cell receptor and high affinity immunoglobulin epsilon receptor signal transduction pathways. It also negatively regulates insulin-like growth factor 1 signaling during muscle atrophy caused by unloading and is involved in EGFR ubiquitination and internalization. Diseases associated with defects in Cbl-b include: multiple sclerosis, autoimmune diseases, including type 1 diabetes, and a craniofacial phenotype. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313 222 KNWTYLAVTHPGYMAFLTYDEVKARLQAYVNKPGSYIFRLSCTRLGQWAIGYVTADGDILQTIPQNKSLFQALVDGQKEG 301
Cdd:cd09920     1 RNWQVLAVTHPGYMAFLTYDEVKARLQKFRDKPGSYVFRLSCTRLGQWAIGYVTADGKILQTIPQNKSLCQALIDGSREG 80

                          90
                  ....*....|....
gi 1974206313 302 FYLYPDGKNVNPDL 315
Cdd:cd09920    81 FYLYPDGRLDNPDL 94

CBL proto-oncogene N-terminal domain 1; Cbl is an adaptor protein that binds EGF receptors (or other tyrosine kinases) and SH3 domains, functioning as a negative regulator of many signaling pathways. The N-terminal domain is evolutionarily conserved, and is known to bind to phosphorylated tyrosine residues. Cbl_N is comprised of 3 structural domains of which this is the first - a four helix bundle.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313  18 RSLEKAFQGLTKLQQLVCQPQMALRNSPPHLPSLLPQIYQHLKLIREHYGTGLAQLWESEFFRIFLLNLLEKIKQATQLF 97
Cdd:pfam02262   4 RTLDKAVKLLDKLVKLCQDPRLNLKNSPPYLLDLLPDTYQHLRLVAEKYRGRLDALGENEYLRIYLANLLAKCKQAAKLF 83

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1974206313  98 KRGKDKeeIFQEASAARRNLTKLSLIFSHMLAELQAVFPN 137
Cdd:pfam02262  84 KEGKEK--MFDEGSRYRRQLTKLSLIFSHMLAELKALFPD 121

RING finger, HC subclass, found in E3 ubiquitin-protein ligase Cbl and similar proteins; Cbl, also known as Casitas B-lineage lymphoma proto-oncogene, proto-oncogene c-Cbl, RING finger protein 55 (RNF55), or signal transduction protein Cbl, is a multi-domain protein that acts as a key negative regulator of various receptor and non-receptor tyrosine kinase signaling. It contains a tyrosine kinase-binding domain (TKB, also known as the phosphotyrosine binding PTB domain, composed of a four helix-bundle, a Ca2+ binding EF-hand and a highly variant SH2 domain), a proline-rich domain, a C3HC4-type RING-HC finger, and an ubiquitin-associated (UBA) domain. TKB is responsible for the interactions with many tyrosine kinases, such as the colony-stimulating factor-1 (CSF-1) receptor, Syk/ZAP-70, and Src-family of protein tyrosine kinases. The proline-rich domain can recruit proteins with a SH3 domain. Moreover, Cbl functions as an E3 ubiquitin ligase that can bind ubiquitin-conjugating enzymes (E2s) through the RING-HC finger.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1974206313 324 RNRIKVSQEQFELYSQVESTFQLCKICAENNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFCRQTIWGHEEVEVSPY 400
Cdd:cd16708     1 QDHIKVTQEQYELYCEMGSTFQLCKICAENDKDVKIEPCGHLMCTSCLTSWQESEGQGCPFCRCEIKGTEPIVVDPF 77

Ring finger; E3 ubiquitin-protein ligase activity is intrinsic to the RING domain of c-Cbl and is likely to be a general function of this domain; Various RING fingers exhibit binding activity towards E2 ubiquitin-conjugating enzymes (Ubc' s)

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|
gi 1974206313  347 CKICAENN-KDVQIRPCGHLLCRECLKSWQLSKSPTCPFC 385
Cdd:smart00184   1 CPICLEEYlKDPVILPCGHTFCRSCIRKWLESGNNTCPIC 40

N1R/p28-like protein; Provisional

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1974206313 347 CKICAEN--NKDVQ------IRPCGHLLCRECLKSWQLSKSpTCPFCRQT 388
Cdd:PHA02929  177 CAICMEKvyDKEIKnmyfgiLSNCNHVFCIECIDIWKKEKN-TCPVCRTP 225

Src homology 2 (SH2) domain found in the Cbl-b TKB domain; SH2 found in the Cbl-b TKB domain. The Cbl (for Casitas B-lineage lymphoma) family of E3 ubiquitin ligases contains three members Cbl, Cbl-b and Cbl-c. The founding member Cbl was discovered first as the oncogenic protein v-Cbl, a Gag-fusion transforming protein of Cas NS-1 retrovirus, which causes pre- and pro-B lymphomas in mice. The N-terminus of the Cbl proteins is composed of a tyrosine kinase-binding (TKB) domain, also called phosphotyrosine binding (PTB) domain, a short linker region and the RING-type zinc finger. In addition, Cbl and Cbl-b contain a leucine zipper motif and a proline-rich domain in the C-terminus. The TKB domain consists of a four-helix bundle (4H), a calcium-binding EF hand and a divergent SH2 domain. Cbl-b plays a role in early hematopoietic development and is a negative regulator of T-cell receptor, B-cell receptor and high affinity immunoglobulin epsilon receptor signal transduction pathways. It also negatively regulates insulin-like growth factor 1 signaling during muscle atrophy caused by unloading and is involved in EGFR ubiquitination and internalization. Diseases associated with defects in Cbl-b include: multiple sclerosis, autoimmune diseases, including type 1 diabetes, and a craniofacial phenotype. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313 222 KNWTYLAVTHPGYMAFLTYDEVKARLQAYVNKPGSYIFRLSCTRLGQWAIGYVTADGDILQTIPQNKSLFQALVDGQKEG 301
Cdd:cd09920     1 RNWQVLAVTHPGYMAFLTYDEVKARLQKFRDKPGSYVFRLSCTRLGQWAIGYVTADGKILQTIPQNKSLCQALIDGSREG 80

                          90
                  ....*....|....
gi 1974206313 302 FYLYPDGKNVNPDL 315
Cdd:cd09920    81 FYLYPDGRLDNPDL 94

CBL proto-oncogene N-terminal domain 1; Cbl is an adaptor protein that binds EGF receptors (or other tyrosine kinases) and SH3 domains, functioning as a negative regulator of many signaling pathways. The N-terminal domain is evolutionarily conserved, and is known to bind to phosphorylated tyrosine residues. Cbl_N is comprised of 3 structural domains of which this is the first - a four helix bundle.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1974206313  18 RSLEKAFQGLTKLQQLVCQPQMALRNSPPHLPSLLPQIYQHLKLIREHYGTGLAQLWESEFFRIFLLNLLEKIKQATQLF 97
Cdd:pfam02262   4 RTLDKAVKLLDKLVKLCQDPRLNLKNSPPYLLDLLPDTYQHLRLVAEKYRGRLDALGENEYLRIYLANLLAKCKQAAKLF 83

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1974206313  98 KRGKDKeeIFQEASAARRNLTKLSLIFSHMLAELQAVFPN 137
Cdd:pfam02262  84 KEGKEK--MFDEGSRYRRQLTKLSLIFSHMLAELKALFPD 121

RING finger, HC subclass, found in E3 ubiquitin-protein ligase Cbl and similar proteins; Cbl, also known as Casitas B-lineage lymphoma proto-oncogene, proto-oncogene c-Cbl, RING finger protein 55 (RNF55), or signal transduction protein Cbl, is a multi-domain protein that acts as a key negative regulator of various receptor and non-receptor tyrosine kinase signaling. It contains a tyrosine kinase-binding domain (TKB, also known as the phosphotyrosine binding PTB domain, composed of a four helix-bundle, a Ca2+ binding EF-hand and a highly variant SH2 domain), a proline-rich domain, a C3HC4-type RING-HC finger, and an ubiquitin-associated (UBA) domain. TKB is responsible for the interactions with many tyrosine kinases, such as the colony-stimulating factor-1 (CSF-1) receptor, Syk/ZAP-70, and Src-family of protein tyrosine kinases. The proline-rich domain can recruit proteins with a SH3 domain. Moreover, Cbl functions as an E3 ubiquitin ligase that can bind ubiquitin-conjugating enzymes (E2s) through the RING-HC finger.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1974206313 324 RNRIKVSQEQFELYSQVESTFQLCKICAENNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFCRQTIWGHEEVEVSPY 400
Cdd:cd16708     1 QDHIKVTQEQYELYCEMGSTFQLCKICAENDKDVKIEPCGHLMCTSCLTSWQESEGQGCPFCRCEIKGTEPIVVDPF 77

RING finger, HC subclass, found in E3 ubiquitin-protein ligase Cbl-c and similar proteins; Cbl-c, also known as RING finger protein 57 (RNF57), SH3-binding protein Cbl-3, SH3-binding protein Cbl-c, or signal transduction protein Cbl-c, is an E3 ubiquitin-protein ligase expressed exclusively in epithelial cells. It contains a tyrosine-kinase-binding domain (TKB, also known as the phosphotyrosine binding PTB domain, composed of a four helix-bundle, a Ca2+ binding EF-hand and a highly variant SH2 domain), a C3HC4-type RING-HC finger, and a short proline-rich region, but lacks the ubiquitin-associated (UBA) leucine zipper motif that are present in Cbl and Cbl-b. Cbl-c acts as a regulator of epidermal growth factor receptor (EGFR)-mediated signal transduction. It also suppresses v-Src-induced transformation through ubiquitin-dependent protein degradation. Moreover, Cbl-c ubiquitinates and downregulates RETMEN2A and implicates Enigma (PDLIM7) as a positive regulator of RETMEN2A by blocking Cbl-mediated ubiquitination and degradation. The ubiquitin ligase activity of Cbl-c is increased via the interaction of its RING-HC finger domain with a LIM domain of the paxillin homolog, hydrogen peroxide induced construct 5 (Hic-5).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1974206313 332 EQFELYSQVESTFQLCKICAENNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFCRQTIWGHEEV 395
Cdd:cd16710     1 EQLQLYQAMNSTFELCKICAERDKDVRIEPCGHLLCSCCLAAWQHSDSQTCPFCRCEIKGREAV 64

Prokaryotic RING finger family 4; RING finger family domain found sporadically in bacteria. The finger is fused to an N-terminal alpha-helical domain, ROT/Trove-like repeats and a C-terminal TerD domain. The architecture suggests a possible role in an RNA-processing complex.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSWQLSkspTCPFCRQTIWGH 392
Cdd:pfam14447   1 CVLCGRNGTVHALIPCGHLVCRDCFDGSDFS---ACPICRRRIDAD 43

HC subclass of RING (RING-HC) finger and its variants; The RING finger is a specialized type of Zn-finger of 40 to 60 residues that binds two atoms of zinc. It is defined by the "cross-brace" motif that chelates zinc atoms by eight amino acid residues, typically Cys or His, arranged in a characteristic spacing. Canonical RING motifs have been categorized into two major subclasses, RING-HC (C3HC4-type) and RING-H2 (C3H2C3-type), according to their Cys/His content. There are also many variants of RING fingers. Some have a different Cys/His pattern. Some lack a single Cys or His residue at typical Zn ligand positions, especially, the fourth or eighth zinc ligand is prevalently exchanged for an Asp, which can chelate Zn in a RING finger as well. This family corresponds to the HC subclass of RING (RING-HC) fingers that are characterized by containing C3HC4-type canonical RING-HC fingers or noncanonical RING-HC finger variants, including C4C4-, C3HC3D-, C2H2C4-, and C3HC5-type modified RING-HC fingers. The canonical RING-HC finger has been defined as C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C. It binds two Zn ions in a unique "cross-brace" arrangement, which distinguishes it from tandem zinc fingers and other similar motifs. RING-HC fingers can be found in a group of diverse proteins with a variety of cellular functions, including oncogenesis, development, viral replication, signal transduction, the cell cycle, and apoptosis. Many of them are ubiquitin-protein ligases (E3s) that serve as scaffolds for binding to ubiquitin-conjugating enzymes (E2s, also referred to as ubiquitin carrier proteins or UBCs) in close proximity to substrate proteins, which enables efficient transfer of ubiquitin from E2 to the substrates.

                          10        20        30
                  ....*....|....*....|....*....|....*....
gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFC 385
Cdd:cd16449     3 CPICLERLKDPVLLPCGHVFCRECIRRLLESGSIKCPIC 41

Zinc finger, C3HC4 type (RING finger); The C3HC4 type zinc-finger (RING finger) is a cysteine-rich domain of 40 to 60 residues that coordinates two zinc ions, and has the consensus sequence: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C where X is any amino acid. Many proteins containing a RING finger play a key role in the ubiquitination pathway.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1974206313 347 CKICAENNKD-VQIRPCGHLLCRECLKSWQLSKSPTCPFC 385
Cdd:pfam00097   1 CPICLEEPKDpVTLLPCGHLFCSKCIRSWLESGNVTCPLC 40

RING finger (Really Interesting New Gene) domain and U-box domain superfamily; The RING finger is a specialized type of Zn-finger of 40 to 60 residues that binds two atoms of zinc. It is defined by the "cross-brace" motif that chelates zinc atoms by eight amino acid residues, typically Cys or His, arranged in a characteristic spacing. Canonical RING motifs have been categorized into two major subclasses, RING-HC (C3HC4-type) and RING-H2 (C3H2C3-type), according to their Cys/His content. There are also many variants of RING fingers: some have different Cys/His patterns while some lack a single Cys or His residue at typical Zn ligand positions (the fourth or eighth zinc ligand is prevalently exchanged for an Asp, which can indeed chelate Zn in a RING finger as well). C4C4-, C3HC3D-, C2H2C4-, and C3HC5-type RING fingers are closely related to RING-HC fingers. In contrast, C4HC3- (RING-CH alias RINGv), C3H3C2-, C3H2C2D-, C3DHC3-, and C4HC2H-type RING fingers are more closely related to RING-H2 fingers. However, not all RING finger-containing proteins display regular RING finger features, and the RING finger family has turned out to be multifarious. The degenerate RING fingers of the Siz/PIAS RING (SP-RING) family proteins and sporulation protein RMD5, are characterized by lacking the second, fifth, and sixth Zn2+ ion-coordinating residues. They bind only one Zn2+ ion. On the other hand, the RING fingers of the human APC11 and RBX1 proteins can bind a third Zn atom since they harbor four additional Zn ligands. U-box is a modified form of the RING finger domain that lacks metal chelating Cys and His residues. It resembles the cross-brace RING structure consisting of three beta-sheets and a single alpha-helix, which would be stabilized by salt bridges instead of chelated metal ions. U-box proteins are widely distributed among eukaryotic organisms and show a higher prevalence in plants than in other organisms. RING finger/U-box-containing proteins are a group of diverse proteins with a variety of cellular functions, including oncogenesis, development, viral replication, signal transduction, the cell cycle and apoptosis. Many of them are ubiquitin-protein ligases (E3s) that serve as scaffolds for binding to ubiquitin-conjugating enzymes (E2s, also referred to as ubiquitin carrier proteins or UBCs) in close proximity to substrate proteins, which enable efficient transfer of ubiquitin from E2 to the substrates.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 1974206313 347 CKICAENNKD---VQIRPCGHLLCRECLKSWQLSKSPTCPFC 385
Cdd:cd00162     1 CPICREEMNDrrpVVLLSCGHTFSRSAIARWLEGSKQKCPFC 42

RING finger, HC subclass, found in Arabidopsis thaliana protein XB3 homolog 5 (XBAT35) and similar proteins; XBAT35, also known as ankyrin repeat domain and RING finger-containing protein XBAT35, or RING-type E3 ubiquitin transferase XBAT35, has no E3 ubiquitin-protein ligase activity observed when associated with the E2 enzyme UBC8 in vitro. It contains a typical C3HC4-type RING-HC finger.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1974206313 347 CKICAENNKDVQIRPCGHL-LCRECLKSWQlSKSPTCPFCRQTI 389
Cdd:cd23129     5 CVVCMDAPRDAVCVPCGHVaGCMSCLKALM-QSSPLCPICRAPV 47

RING finger, HC subclass, found in RING finger protein 213 (RNF213) and similar proteins; RNF213, also known as ALK lymphoma oligomerization partner on chromosome 17 or Moyamoya steno-occlusive disease-associated AAA+ and RING finger protein (mysterin), is an intracellular soluble protein that functions as an E3 ubiquitin-protein ligase and AAA+ ATPase, which possibly contributes to vascular development through mechanical processes in the cell. It plays a unique role in endothelial cells for proper gene expression in response to inflammatory signals from the environment. Mutations in RNF213 may be associated with Moyamoya disease (MMD), an idiopathic cerebrovascular occlusive disorder prevalent in East Asia. It also acts as a nuclear marker for acanthomorph phylogeny. RNF213 contains two tandem enzymatically active AAA+ ATPase modules and a C3HC4-type RING-HC finger. It can form a huge ring-shaped oligomeric complex.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1974206313 345 QLCKICAENNKDVQIRPCGHLLCRECLKSWqLSKSPTCPFCRQ 387
Cdd:cd16561     3 QECSICLEDLNDPVKLPCDHVFCEECIRQW-LPGQMSCPLCRT 44

RING finger, HC subclass, found in inhibitor of apoptosis proteins (IAPs); IAPs are frequently overexpressed in cancer and associated with tumor cell survival, chemoresistance, disease progression, and poor prognosis. They function primarily as negative regulators of cell death. They regulate caspases and apoptosis through the inhibition of specific members of the caspase family of cysteine proteases. In addition, IAPs has been implicated in a multitude of other cellular processes, including inflammatory signalling and immunity, mitogenic kinase signalling, proliferation and mitosis, as well as cell invasion and metastasis. IAPs in this family includes cellular inhibitor of apoptosis protein c-IAP1 (BIRC2) and c-IAP2 (BIRC3), XIAP (BIRC4), BIRC7, and BIRC8, all of which contain three N-terminal baculoviral IAP repeat (BIR) domains that enable interactions with proteins, a ubiquitin-association (UBA) domain that is responsible for the binding of polyubiquitin (polyUb), and a C3HC4-type RING-HC finger at the carboxyl terminus that is required for ubiquitin ligase activity. The UBA domain is only absent in mammalian homologs of BIRC7. Moreover, c-IAPs contains an additional caspase activation and recruitment domain (CARD) between the UBA and C3HC4-type RING-HC domains. The CARD domain may serve as a protein interaction surface.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1974206313 345 QLCKICAENNKDVQIRPCGHLL-CRECLKSWQlskspTCPFCRQ 387
Cdd:cd16510     2 KLCKICMDREVNIVFLPCGHLVtCAQCAASLR-----KCPICRT 40

RING finger, H2 subclass, found in TRAF-interacting protein (TRAIP) and similar proteins; TRAIP, also known as RING finger protein 206 (RNF206) or TRIP, is a ubiquitously expressed nucleolar E3 ubiquitin ligase important for cellular proliferation and differentiation. It is found near mitotic chromosomes and functions as a regulator of the spindle assembly checkpoint. TRAIP interacts with tumor necrosis factor (TNF)-receptor-associated factor (TRAF) proteins and inhibits TNF-alpha-mediated nuclear factor (NF)-kappaB activation. It also interacts with two tumor suppressors CYLD and spleen tyrosine kinase (Syk), and DNA polymerase eta, which facilitates translesional synthesis after DNA damage. TRAIP contains an N-terminal C3H2C2-type RING-H2 finger and an extended coiled-coil domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1974206313 346 LCKICAE---NNKDVQIRPCGHLLCRECLKSWqLSKSPTCPFCR 386
Cdd:cd16480     1 YCTICSDffdNSRDVAAIHCGHTFHYDCLLQW-FDTSRTCPQCR 43

Modified RING finger, HC subclass (C3HC5-type), found in RING finger proteins, RNF26, RNF197 (CGRRF1), RNF156 (MGRN1), RNF157 and similar proteins; This subfamily corresponds to a group of RING finger proteins containing a modified C3HC5-type RING-HC finger, which is distinguished from typical C3HC4 RING-HC finger due to the existence of the additional cysteine residue in the middle portion of the RING finger domain. Cell growth regulator with RING finger domain protein 1 (CGRRF1), also known as cell growth regulatory gene 19 protein (CGR19) or RING finger protein 197 (RNF197), functions as a novel biomarker to monitor endometrial sensitivity and response to insulin-sensitizing drugs, such as metformin, in the context of obesity. RNF26 is an E3 ubiquitin ligase that temporally regulates virus-triggered type I interferon induction by increasing the stability of Mediator of IRF3 activation, MITA, also known as STING, through K11-linked polyubiquitination after viral infection and promoting degradation of IRF3, another important component required for virus-triggered interferon induction. Mahogunin ring finger-1 (MGRN1), also known as RING finger protein 156 (RNF156), is a cytosolic E3 ubiquitin-protein ligase that inhibits signaling through the G protein-coupled melanocortin receptors-1 (MC1R), -2 (MC2R) and -4 (MC4R) via ubiquitylation-dependent and -independent processes. It suppresses chaperone-associated misfolded protein aggregation and toxicity. RNF157 is a cytoplasmic E3 ubiquitin ligase predominantly expressed in the brain. It is a homolog of the E3 ligase MGRN1. In cultured neurons, it promotes neuronal survival in an E3 ligase-dependent manner. In contrast, it supports growth and maintenance of dendrites independent of its E3 ligase activity. RNF157 interacts with and ubiquitinates the adaptor protein APBB1 (amyloid beta precursor protein-binding, family B, member 1 or Fe65), which regulates neuronal survival, but not dendritic growth downstream of RNF157. The nuclear localization of APBB1 together with its interaction partner RNA-binding protein SART3 (squamous cell carcinoma antigen recognized by T cells 3 or Tip110) is crucial to trigger apoptosis.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1974206313 345 QLCKICAENNKDVQIRPCGHL-LCRECLKSwqlSKSPTCPFCR 386
Cdd:cd16649     1 GLCVVCLENPASVLLLPCRHLcLCEVCAKG---LRGKTCPICR 40

RING finger, HC subclass, found in Arabidopsis thaliana protein XB3 homolog 1 (XBAT31) and similar proteins; XBAT31, also called ankyrin repeat domain and RING finger-containing protein XBAT31, or RING-type E3 ubiquitin transferase XB31, has no E3 ubiquitin-protein ligase activity observed when associated with the E2 enzyme UBC8 in vitro. XBAT31 contains a typical C3HC4-type RING-HC finger.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 1974206313 342 STFQLCKICAENNKDVQIRPCGHLLCRECL----------KSWQLSKSPTCPFCRQTI 389
Cdd:cd23144     4 SDEDVCCICFEHLCTIEIKDCGHQMCATCAlklcchnkpnPSSSPPRPPACPFCRQDI 61

RING finger, HC subclass, found in caspases-8 and -10-associated RING finger protein CARP-1, CARP-2 and similar proteins; The CARP subfamily includes CARP-1 and CARP-2 proteins, both of which are E3 ubiquitin ligases that ubiquitinate apical caspases and target them for proteasome-mediated degradation. As a novel group of caspase regulators with a FYVE-type zinc finger domain, they do not localize to membranes in the cell and are involved in the negative regulation of apoptosis, specifically targeting two initiator caspases, caspase 8, and caspase 10. Moreover, they stabilize MDM2 by inhibiting MDM2 self-ubiquitination, as well as by targeting 14-3-3sigma for degradation. They work together with MDM2 to enhance p53 degradation, thereby inhibiting p53-mediated cell death. CARPs contain an N-terminal FYVE-like domain that can serve as a membrane-targeting or endosome localizing signal and a C-terminal C3HC4-type RING-HC finger domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCreCLK-SWQLSKsptCPFCRQTI 389
Cdd:cd16500     2 LCKICMDAAIDCVLLECGHMVT--CTDcGKKLSE---CPICRQYV 41

RING finger, HC subclass, found in RING finger protein 185 (RNF185) and similar proteins; RNF185 is an E3 ubiquitin-protein ligase of endoplasmic reticulum-associated degradation (ERAD) that targets cystic fibrosis transmembrane conductance regulator (CFTR). It controls the degradation of CFTR and CFTR F508del allele in a RING- and proteasome-dependent manner, but does not control that of other classical ERAD model substrates. It also negatively regulates osteogenic differentiation by targeting dishevelled2 (Dvl2), a key mediator of the Wnt signaling pathway, for degradation. Moreover, RNF185 regulates selective mitochondrial autophagy through interaction with the Bcl-2 family protein BNIP1. It also plays an important role in cell adhesion and migration through the modulation of cell migration by ubiquitinating paxillin. RNF185 contains a C3HC4-type RING-HC finger.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSWQLSK--SPTCPFCRQTI 389
Cdd:cd16744     3 CNICLDTAKDAVVSLCGHLFCWPCLHQWLETRpnRQVCPVCKAGI 47

RING finger, HC subclass, found in bifunctional apoptosis regulator (BAR); BAR, also known as RING finger protein 47, was originally identified as an inhibitor of Bax-induced apoptosis. It participates in the block of apoptosis induced by TNF-family death receptors (extrinsic pathway) and mitochondria-dependent apoptosis (intrinsic pathway). BAR is predominantly expressed by neurons in the central nervous system and is involved in the regulation of neuronal survival. It is an endoplasmic reticulum (ER)-associated RING-type E3 ubiquitin ligase that interacts with BI-1 protein and post-translationally regulates its stability, as well as functioning in ER stress. BAR contains an N-terminal C3HC4-type RING-HC finger, a SAM domain, a coiled-coil domain, and a C-terminal transmembrane (TM) domain. This model corresponds to the RING-HC finger responsible for the binding of ubiquitin conjugating enzymes (E2s).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCRECLKSWQL-SKSPTCPFCRQTIWGH 392
Cdd:cd16497     3 LCHCCYDLLVNPTTLNCGHSFCRHCLALWWKsSKKTECPECRQKWEGF 50

RING finger, HC subclass, found in RING finger protein 138 (RNF138) and similar proteins; RNF138, also known as Nemo-like kinase-associated RING finger protein (NARF) or NLK-associated RING finger protein, is an E3 ubiquitin-protein ligase that plays an important role in glioma cell proliferation, apoptosis, and cell cycle. It specifically cooperates with the E2 conjugating enzyme E2-25K (Hip-2/UbcH1), regulates the ubiquitylation and degradation of T cell factor/lymphoid enhancer factor (TCF/LEF), and further suppresses Wnt-beta-catenin signaling. RNF138, together with three closely related proteins: RNF114, RNF125 and RNF166, forms a novel family of ubiquitin ligases with a C3HC4-type RING-HC finger, a C2HC-, and two C2H2-type zinc fingers, as well as a ubiquitin interacting motif (UIM).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1974206313 346 LCKICAENNKD-VQIRPCGHLLCRECLKSWQLSKSPTCPFCRQTIWGHE 393
Cdd:cd16544     4 TCPVCQEVLKDpVELPPCRHIFCKACILLALRSSGARCPLCRGPVGKTE 52

Modified RING finger, HC subclass (C3HC5-type), found in mitochondrial-anchored protein ligase (MAPL) and similar proteins; MAPL, also known as MULAN, mitochondrial ubiquitin ligase activator of NFKB 1, E3 SUMO-protein ligase MUL1, E3 ubiquitin-protein ligase MUL1, growth inhibition and death E3 ligase (GIDE), putative NF-kappa-B-activating protein 266, or RING finger protein 218 (RNF218), is a multifunctional mitochondrial outer membrane protein involved in several processes specific to metazoan (multicellular animal) cells, such as NF-kappaB activation, innate immunity and antiviral signaling, suppression of PINK1/parkin defects, mitophagy in skeletal muscle, and caspase-dependent apoptosis. MAPL contains a unique BAM (beside a membrane)/GIDE (growth inhibition death E3 ligase) domain and a C-terminal modified cytosolic C3HC5-type RING-HC finger which is distinguished from typical C3HC4-type RING-HC finger due to the existence of the additional cysteine residue in the middle portion of the RING finger domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1974206313 347 CKICAENNKDVQIRPCGHL-LCRECLKSwqLSKSPTCPFCRQTI 389
Cdd:cd16648     4 CVICLSNPRSCVFLECGHVcSCIECYEA--LPSPKKCPICRSFI 45

RING finger, HC subclass, found in RING domain ligase RGLG1, RGLG2 and similar proteins from plant; RGLG1 is a ubiquitously expressed E3 ubiquitin-protein ligase that interacts with UBC13 and, together with UBC13, catalyzes the formation of K63-linked polyubiquitin chains, which is involved in DNA damage repair. RGLG1 mediates the formation of canonical, K48-linked polyubiquitin chains that target proteins for degradation. It also regulates apical dominance by acting on the auxin transport proteins abundance. RGLG1 has overlapping functions with its closest sequelog, RGLG2. They both function as RING E3 ligases that interact with ethylene response factor 53 (ERF53) in the nucleus and negatively regulate the plant drought stress response. Members of this subfamily contain a Von Willebrand factor type A (vWA) domain and a C3HC4-type RING-HC finger.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1974206313 345 QLCKICAENNKDVQIRpCGHLLCRECLKSWQlskspTCPFCRQTI 389
Cdd:cd16729     3 QLCPICLSNPKDMAFG-CGHQTCCECGQSLT-----HCPICRQPI 41

RING finger, HC subclass, found in RING finger protein RNF5, RNF185 and similar proteins; RNF5 and RNF185 are E3 ubiquitin-protein ligases that are anchored to the outer membrane of the endoplasmic reticulum (ER). RNF5 acts at early stages of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) biosynthesis, and functions as a target for therapeutic modalities to antagonize mutant CFTR proteins in CF patients carrying the F508del allele. RNF185 controls the degradation of CFTR and CFTR F508del allele in a RING- and proteasome-dependent manner, but does not control that of other classical endoplasmic reticulum-associated degradation (ERAD) model substrates. Moreover, both RNF5 and RNF185 play important roles in cell adhesion and migration through the modulation of cell migration by ubiquitinating paxillin. Arabidopsis thaliana RING membrane-anchor proteins (AtRMAs) are also included in this family. They possess E3 ubiquitin-protein ligase activity and may play a role in the growth and development of Arabidopsis. All members of this family contain a C3HC4-type RING-HC finger.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSW--QLSKSPTCPFCR 386
Cdd:cd16534     3 CNICLDTASDPVVTMCGHLFCWPCLYQWleTRPDRQTCPVCK 44

RING finger, HC subclass, found in RING finger protein 166 (RNF166) and similar proteins; RNF166 is encoded by the gene RNF166 targeted by thyroid hormone receptor alpha1 (TRalpha1), which is important in brain development. It plays an important role in RNA virus-induced interferon-beta production by enhancing the ubiquitination of TRAF3 and TRAF6. RNF166, together with three closely related proteins: RNF114, RNF125 and RNF138, forms a novel family of ubiquitin ligases with a C3HC4-type RING-HC finger, a C2HC-, and two C2H2-type zinc fingers, as well as a ubiquitin interacting motif (UIM).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 1974206313 347 CKICAE-NNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFCR 386
Cdd:cd16549     4 CPICLEvYHKPVVITSCGHTFCGECLQPCLQVASPLCPLCR 44

RING finger, H2 subclass, found in the PA-TM-RING ubiquitin ligase family; The PA-TM-RING family represents a group of transmembrane-type E3 ubiquitin ligases, which has been characterized by an N-terminal transient signal peptide, a PA (protease-associated) domain, a TM (transmembrane) domain, as well as a C-terminal C3H2C3-type RING-H2 finger domain. It includes RNF13, RNF167, ZNRF4 (zinc and RING finger 4), GRAIL (gene related to anergy in lymphocytes)/RNF128, RNF130, RNF133, RNF148, RNF149 and RNF150 (which are more closely related), as well as RNF43 and ZNRF3, which have substantially longer C-terminal tail extensions compared with the others. PA-TM-RING proteins are expressed at low levels in all mammalian tissues and species, but they are not present in yeast. They play a common regulatory role in intracellular trafficking/sorting, suggesting that abrogation of their function may result in dysregulation of cellular signaling events in cancer.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1974206313 347 CKICAEN---NKDVQIRPCGHLLCRECLKSWqLSKSPTCPFCR 386
Cdd:cd16454     2 CAICLEEfkeGEKVRVLPCNHLFHKDCIDPW-LEQHNTCPLCR 43

RING finger, HC subclass, found in Arabidopsis thaliana SP1-like protein 2 (SPL2) and similar proteins; SPL2, also known as RING-type E3 ubiquitin transferase SPL2, acts as an E3 ubiquitin-protein ligase that mediates E2-dependent protein ubiquitination. SPL2 contains a typical C3HC4-type RING-HC finger.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1974206313 345 QLCKICAENNKDVQIRPCGHLL-CRECLKSWQLSKSPTCPFCRQ 387
Cdd:cd23145     4 ELCVVCLLRRRRVAFIECGHRVcCELCARRVTREANPRCPVCRQ 47

RING finger, H2 subclass, found in protein E3 ubiquitin-protein ligase Praja-1, Praja-2, and similar proteins; This family includes two highly similar E3 ubiquitin-protein ligases, Praja-1 and Praja-2. Praja-1, also known as RING finger protein 70, is a RING-H2 finger ubiquitin ligase encoded by gene PJA1, a novel human X chromosome gene abundantly expressed in the brain. It has been implicated in bone and liver development, as well as memory formation and X-linked mental retardation (MRX). Praja-1 interacts with and activates the ubiquitin-conjugating enzyme UbcH5B, and shows E2-dependent E3 ubiquitin ligase activity. It is a 3-deazaneplanocin A (DZNep)-induced ubiquitin ligase that directly ubiquitinates individual polycomb repressive complex 2 (PRC2) subunits in a cell free system, which leads to their proteasomal degradation. It also plays an important role in neuronal plasticity, which is the basis for learning and memory. Moreover, Praja-1 ubiquitinates embryonic liver fodrin (ELF) and Smad3, but not Smad4, in a transforming growth factor-beta (TGF-beta)-dependent manner. It controls ELF abundance through ubiquitin-mediated degradation, and further regulates TGF-beta signaling, which plays a key role in the suppression of gastric carcinoma. Praja-1 also regulates the transcription function of the homeodomain protein Dlx5 by controlling the stability of Dlxin-1, via a ubiquitin-dependent degradation pathway. Praja-2, also known as RING finger protein 131, NEURODAP1, or KIAA0438, is an E2-dependent E3 ubiquitin ligase that interacts with and activates the ubiquitin-conjugating enzyme UbcH5B. It functions as an A-kinase anchoring protein (AKAP)-like E3 ubiquitin ligase that plays a critical role in controlling cyclic AMP (cAMP)-dependent PKA activity and pro-survival signaling, and further promotes cell proliferation and growth. Praja-2 is also involved in protein sorting at the postsynaptic density region of axosomatic synapses and possibly plays a role in synaptic communication and plasticity. Together with the AMPK-related kinase SIK2 and the CDK5 activator CDK5R1/p35, it forms a SIK2-p35-PJA2 complex that plays an essential role for glucose homeostasis in pancreatic beta cell functional compensation. Praja-2 ubiquitylates and degrades Mob, a core component of NDR/LATS kinase and a positive regulator of the tumor-suppressor Hippo signaling. Both Praja-1 and Praja-2 contain a potential nuclear localization signal (NLS) and a C-terminal C3H2C3-type RING-H2 motif.

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                  ....*....|....*....|....*....|....*....|....*.
gi 1974206313 347 CKIC-AENNKD--VQIRPCGHLLCRECLKSWqLSKSPTCPFCRQTI 389
Cdd:cd16465     2 CPICcSEYVKDeiATELPCHHLFHKPCITAW-LQKSGTCPVCRHVL 46

RING finger, HC subclass, found in Saccharomyces cerevisiae increased recombination centers protein 20 (IRC20) and similar proteins; IRC20 is an uncharacterized ATP-dependent helicase that is probably involved in a pathway contributing to genomic integrity. IRC20 contains a typical C3HC4-type RING-HC finger.

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                  ....*....|....*....|....*....|....*....|
gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSWQLSKSpTCPFCR 386
Cdd:cd23135     6 CSICFSEIRSGAILKCGHFFCLSCIASWLREKS-TCPLCK 44

RING finger, H2 subclass, found in synoviolin and similar proteins; Synoviolin, also known as synovial apoptosis inhibitor 1 (Syvn1), Hrd1, or Der3, is an endoplasmic reticulum (ER)-anchoring E3 ubiquitin ligase that functions as a suppressor of ER stress-induced apoptosis and plays a role in homeostasis maintenance. It also targets tumor suppressor gene p53 for proteasomal degradation, suggesting crosstalk between ER associated degradation (ERAD) and p53 mediated apoptotic pathway under ER stress. Moreover, synoviolin controls body weight and mitochondrial biogenesis through negative regulation of the thermogenic coactivator peroxisome proliferator-activated receptor coactivator (PGC)-1beta. It upregulates amyloid beta production by targeting a negative regulator of gamma-secretase, Retention in endoplasmic reticulum 1 (Rer1), for degradation. It is also involved in the degradation of endogenous immature nicastrin, and affects amyloid beta-protein generation. Moreover, synoviolin is highly expressed in rheumatoid synovial cells and may be involved in the pathogenesis of rheumatoid arthritis (RA). It functions as an anti-apoptotic factor that is responsible for the outgrowth of synovial cells during the development of RA. It promotes inositol-requiring enzyme 1 (IRE1) ubiquitination and degradation in synovial fibroblasts with collagen-induced arthritis. Furthermore, the upregulation of synoviolin may represent a protective response against neurodegeneration in Parkinson's disease (PD). In addition, synoviolin is involved in liver fibrogenesis. Synoviolin contains a C3H2C2-type RING-H2 finger.

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gi 1974206313 345 QLCKICAENNKDVQIR-PCGHLLCRECLKSWqLSKSPTCPFCR 386
Cdd:cd16479     2 NTCIICREEMTVGAKKlPCGHIFHLSCLRSW-LQRQQTCPTCR 43

Modified RING finger, HC subclass (C3HC5-type), found in RING finger protein 26 (RNF26) and similar proteins; RNF26 is an E3 ubiquitin ligase that temporally regulates virus-triggered type I interferon induction by increasing the stability of Mediator of IRF3 activation, MITA, also known as STING, through K11-linked polyubiquitination of MITA after viral infection, and promoting the degradation of IRF3, another important component required for virus-triggered interferon induction. Although RNF26 substrates of ubiquitination remain unclear at present, RNF26 upregulation in gastric cancer might be implicated in carcinogenesis through dysregulation of growth regulators. RNF26 contains an N-terminal leucine zipper domain and a C-terminal modified C3HC5-type RING-HC finger, which is distinguished from typical C3HC4 RING-HC finger due to the existence of the additional cysteine residue in the middle portion of the RING finger domain.

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                  ....*....|....*....|....*....|....*....|....*....
gi 1974206313 346 LCKICAENNKDVQIRPCGHL-LCRECLKswQLSKSPT----CPFCRQTI 389
Cdd:cd16788     7 KCVICQDQSKTVLILPCRHMcLCRQCAN--ILLQQPVyrrnCPLCRTMI 53

RING-type zinc-finger; This zinc-finger is a typical RING-type of plant ubiquitin ligases.

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gi 1974206313 347 CKICAENNKDVQIrPCGHLLCRECL--KSWQLSKSPTCP 383
Cdd:pfam13445   1 CPICLELFTDPVL-PCGHTFCRECLeeMSQKKGGKFKCP 38

H2 subclass of RING (RING-H2) fingers and its variants; The RING finger is a specialized type of Zn-finger of 40 to 60 residues that binds two atoms of zinc. It is defined by the "cross-brace" motif that chelates zinc atoms by eight amino acid residues, typically Cys or His, arranged in a characteristic spacing. Canonical RING motifs have been categorized into two major subclasses, RING-HC (C3HC4-type) and RING-H2 (C3H2C3-type), according to their Cys/His content. There are also many variants of RING fingers: some have different Cys/His patterns while some lack a single Cys or His residue at typical Zn ligand positions (the fourth or eighth zinc ligand is prevalently exchanged for an Asp, which can indeed chelate Zn in a RING finger as well). This family corresponds to the H2 subclass of RING (RING-H2) finger proteins that are characterized by containing C3H2C3-type canonical RING-H2 fingers or noncanonical RING-H2 finger variants, including C4HC3- (RING-CH alias RINGv), C3H3C2-, C3H2C2D-, C3DHC3-, and C4HC2H-type modified RING-H2 fingers. The canonical RING-H2 finger has been defined as C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-H-X2-C-X(4-48)-C-X2-C, X is any amino acid and the number of X residues varies in different fingers. It binds two Zn ions in a unique "cross-brace" arrangement, which distinguishes it from tandem zinc fingers and other similar motifs. RING-H2 finger can be found in a group of diverse proteins with a variety of cellular functions, including oncogenesis, development, viral replication, signal transduction, the cell cycle and apoptosis. Many of them are ubiquitin-protein ligases (E3s) that serves as a scaffold for binding to ubiquitin-conjugating enzymes (E2s, also referred to as ubiquitin carrier proteins or UBCs) in close proximity to substrate proteins, which enables efficient transfer of ubiquitin from E2 to the substrates.

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gi 1974206313 347 CKICAEN--NKDVQIR-PCGHLLCRECLKSWQLSKSPTCPFCR 386
Cdd:cd16448     1 CVICLEEfeEGDVVRLlPCGHVFHLACILRWLESGNNTCPLCR 43

Modified RING finger, HC subclass (C2H2C4-type), found in E3 ubiquitin-protein ligase MDM2, protein MDM4 and similar proteins; MDM2 (also known as HDM2) and MDM4 (also known as MDMX or HDMX) are the primary p53 tumor suppressor negative regulators. They have non-redundant roles in the regulation of p53. MDM2 mainly functions to control p53 stability, while MDM4 controls p53 transcriptional activity. Both MDM2 and MDM4 contain an N-terminal p53-binding domain, a RanBP2-type zinc finger (zf-RanBP2) domain near the central acidic region, and a C-terminal modified C2H2C4-type RING-HC finger. Mdm2 can form homo-oligomers through its RING domain and displays E3 ubiquitin ligase activity that catalyzes the attachment of ubiquitin to p53 as an essential step in the regulation of its levels in cells. Despite its RING domain and structural similarity with MDM2, MDM4 does not homo-oligomerize and lacks ubiquitin-ligase function, but inhibits the transcriptional activity of p53. In addition, both their RING domains are responsible for the hetero-oligomerization, which is crucial for the suppression of P53 activity during embryonic development and the recruitment of E2 ubiquitin-conjugating enzymes. Moreover, MDM2 and MDM4 can be phosphorylated and destabilized in response to DNA damage stress. In response to ribosomal stress, MDM2-mediated p53 ubiquitination and degradation can be inhibited through the interaction with ribosomal proteins L5, L11, and L23. However, MDM4 is not bound to ribosomal proteins, suggesting its different response to regulation by small basic proteins such as ribosomal proteins and ARF.

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gi 1974206313 346 LCKICAENNKDVQI--RPCGHLL-CRECLKSWQLSKSPtCPFCRQTI 389
Cdd:cd16646     2 LCVICLSRPRTAAIvhGKTGHQVaCYTCAKKLKRRGKP-CPVCRRPI 47

RING finger, HC subclass, found in RNA-binding proteins of the evolutionarily-conserved MEX-3 family; MEX-3 phosphoproteins are found in vertebrates. They are mediators of post-transcriptional regulation in different organisms, and have been implicated in many core biological processes, including embryonic development, epithelial homeostasis, immune responses, metabolism, and cancer. They contain two K homology (KH) domains that provide RNA-binding capacity, and a C-terminal C3HC4-type RING-HC finger. They shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway. The RNA-binding protein MEX-3 from nematode Caenorhabditis elegans is the founding member of the MEX-3 family. Due to the lack of a RING-HC finger, it is not included here.

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gi 1974206313 347 CKICAENNKDVQIRPCGH-LLCRECLKSWQLSKSPTCPFCRQTI 389
Cdd:cd16518     3 CVVCFESEVVAALVPCGHnLFCMECANRICEKSDPECPVCHTPV 46

Modified RING finger, HC subclass (C3HC5-type), found in mahogunin RING finger protein 1 (MGRN1), RING finger protein 157 (RNF157) and similar proteins; MGRN1, also known as RING finger protein 156 (RNF156), is a cytosolic E3 ubiquitin-protein ligase that inhibits signaling through the G protein-coupled melanocortin receptors-1 (MC1R), -2 (MC2R) and -4 (MC4R) via ubiquitylation-dependent and -independent processes. It suppresses chaperone-associated misfolded protein aggregation and toxicity. MGRN1 interacts with cytosolic prion proteins (PrPs) that are linked with neurodegeneration. It also interacts with expanded polyglutamine proteins, and suppresses misfolded polyglutamine aggregation and cytotoxicity. Moreover, MGRN1 inhibits melanocortin receptor signaling by competition with Galphas, suggesting a novel pathway for melanocortin signaling from the cell surface to the nucleus. MGRN1 also interacts with and ubiquitylates TSG101, a key component of the endosomal sorting complex required for transport (ESCRT)-I, and regulates endosomal trafficking. A null mutation in the gene encoding MGRN1 causes spongiform neurodegeneration, suggesting a link between dysregulation of endosomal trafficking and spongiform neurodegeneration. RNF157 is a cytoplasmic E3 ubiquitin ligase predominantly expressed in the brain. It is a homolog of the E3 ligase mahogunin ring finger-1 (MGRN1). In cultured neurons, it promotes neuronal survival in an E3 ligase-dependent manner. In contrast, it supports growth and maintenance of dendrites independent of its E3 ligase activity. RNF157 interacts with and ubiquitinates the adaptor protein APBB1 (amyloid beta precursor protein-binding, family B, member 1 or Fe65), which regulates neuronal survival, but not dendritic growth downstream of RNF157. The nuclear localization of APBB1 together with its interaction partner RNA-binding protein SART3 (squamous cell carcinoma antigen recognized by T cells 3 or Tip110) is crucial to trigger apoptosis. Both MGRN1 and RNF157 contain a modified C3HC5-type RING-HC finger, and a functionally uncharacterized region, known as domain associated with RING2 (DAR2), N-terminal to the RING finger. The C3HC5-type RING-HC finger is distinguished from typical C3HC4 RING-HC finger due to the existence of the additional cysteine residue in the middle portion of the RING finger domain.

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                  ....*....|....*....|....*....|....*....|..
gi 1974206313 346 LCKICAENNKDVQIRPCGHL-LCRECLKSWQLSkSPTCPFCR 386
Cdd:cd16789     2 ECVICLSDPRDTAVLPCRHLcLCSDCAEVLRYQ-SNKCPICR 42

RING finger, HC subclass, found in tripartite motif-containing protein TRIM25 and similar proteins; TRIM25, also known as estrogen-responsive finger protein (EFP), RING finger protein 147 (RNF147), or RING-type E3 ubiquitin transferase, is an E3 ubiquitin/ISG15 ligase that is induced by estrogen and is therefore particularly abundant in placenta and uterus. TRIM25 regulates various cellular processes through E3 ubiquitin ligase activity, transferring ubiquitin and ISG15 to target proteins. It mediates K63-linked polyubiquitination of retinoic acid inducible gene I (RIG-I) that is crucial for downstream antiviral interferon signaling. It is also required for melanoma differentiation-associated gene 5 (MDA5) and mitochondrial antiviral signaling (MAVS, also known as IPS-1, VISA, Cardiff) mediated activation of nuclear factor-kappaB (NF-kappaB) and interferon production. Upon UV irradiation, TRIM25 interacts with mono-ubiquitinated PCNA and promotes its ISG15 modification (ISGylation), suggesting a crucial role in termination of error-prone translesion DNA synthesis. TRIM25 also functions as a novel regulator of p53 and Mdm2. It enhances p53 and Mdm2 abundance by inhibiting their ubiquitination and degradation in 26S proteasomes. Meanwhile, it inhibits p53's transcriptional activity and dampens the response to DNA damage, and is essential for medaka development and this dependence is rescued by silencing of p53. Moreover, TRIM25 is involved in the host cellular innate immune response against retroviral infection. It interferes with the late stage of feline leukemia virus (FeLV) replication. Furthermore, TRIM25 acts as an oncogene in gastric cancer. Its blockade by RNA interference inhibits migration and invasion of gastric cancer cells through transforming growth factor-beta (TGF-beta) signaling, suggesting it presents a novel target for the detection and treatment of gastric cancer. In addition, TRIM25 acts as an RNA-specific activator for Lin28a/TuT4-mediated uridylation. TRIM25 belongs to the C-IV subclass of TRIM (tripartite motif) family of proteins that are defined by their N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as a B30.2/SPRY (SplA and ryanodine receptor) domain positioned C-terminal to the RBCC domain.

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gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECL-KSW--QLSKSPTCPFCRQT 388
Cdd:cd16597     8 CSICLELFKDPVTLPCGHNFCGVCIeKTWdsQHGSEYSCPQCRAT 52

RING finger, HC subclass, found in tripartite motif-containing protein 62 (TRIM62) and similar proteins; TRIM62, also known as Ductal Epithelium Associated Ring Chromosome 1 (DEAR1), is a cytoplasmic E3 ubiquitin-protein ligase that was identified as a dominant regulator of acinar morphogenesis in the mammary gland. It is implicated in the inflammatory response of immune cells by regulating the Toll-like receptor 4 (TLR4) signaling pathway, leading to increased activity of the activator protein 1 (AP-1) transcription factor in primary macrophages. It is also involved in muscular protein homeostasis, especially during inflammation-induced atrophy, and may play a role in the pathogenesis of ICU-acquired weakness (ICUAW) by activating and maintaining inflammation in myocytes. Moreover, TRIM62 facilitates K27-linked poly-ubiquitination of CARD9 and also regulates CARD9-mediated anti-fungal immunity and intestinal inflammation. It also functions as a chromosome 1p35 tumor suppressor and negatively regulates transforming growth factor beta (TGFbeta)-driven epithelial-mesenchymal transition (EMT) by binding to and promoting the ubiquitination of SMAD3, a major effector of TGFbeta-mediated EMT. TRIM62 belongs to the C-IV subclass of the TRIM (tripartite motif) family of proteins that are defined by their N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as a B30.2/SPRY (SplA and ryanodine receptor) domain positioned C-terminal to the RBCC domain.

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gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCRECLKS-WQLSKSPTCPFCRQT 388
Cdd:cd16608     8 LCSICLSIYQDPVSLGCEHYFCRQCITEhWSRSEHRDCPECRRT 51

RING finger, HC subclass, found in RING finger protein 114 (RNF114) and similar proteins; RNF114, also known as zinc finger protein 228 (ZNF228) or zinc finger protein 313 (ZNF313), is a p21(WAF1)-targeting ubiquitin E3 ligase that interacts with X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) and may play a role in p53-mediated cell-fate decisions. It is involved in the immune response to double-stranded RNA in disease pathogenesis. Moreover, RNF114 interacts with A20 and modulates its ubiquitylation. It negatively regulates nuclear factor-kappaB (NF-kappaB)-dependent transcription and positively regulates T-cell activation. RNF114 may play a putative role in the regulation of immune responses, since it corresponds to a novel psoriasis susceptibility gene, ZNF313. RNF114, together with three closely related proteins: RNF125, RNF138 and RNF166, forms a novel family of ubiquitin ligases with a C3HC4-type RING-HC finger, a C2HC-, and two C2H2-type zinc fingers, as well as a ubiquitin interacting motif (UIM).

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gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCRECLKSWQLSKSPTCPFCR 386
Cdd:cd16540     3 TCPVCLEIFETPVRVPCGHVFCNACLQECLKPKKPVCAVCR 43

Modified RING finger, HC subclass (C3HC5-type), found in neuralized-like protein NEURL1A, NEURL1B, and similar proteins; This subfamily includes Drosophila neuralized (D-neu) protein, and its two mammalian homologs, NEURL1A and NEURL1B. D-neu is a regulator of the developmentally important Notch signaling pathway. NEURL1A, also known as NEURL1, NEU, neuralized 1, or RING finger protein 67 (RNF67), is a mammalian homolog of D-neu. It functions as an E3 ubiquitin-protein ligase that directly interacts with and monoubiquitinates cytoplasmic polyadenylation element-binding protein 3 (CPEB3), an RNA binding protein and a translational regulator of local protein synthesis, which facilitates hippocampal plasticity and hippocampal-dependent memory storage. It also acts as a potential tumor suppressor that causes apoptosis and downregulates Notch target genes in medulloblastoma. NEURL1B, also known as neuralized-2 (NEUR2) or neuralized-like protein 3, is another mammalian homolog of D-neu protein. It functions as an E3 ubiquitin-protein ligase that interacts with and ubiquitinates Delta. Thus, it plays a role in the endocytic pathways for Notch signaling by working cooperatively with another E3 ligase, Mind bomb-1 (Mib1), in Delta endocytosis to hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs)-positive vesicles. Members of this subfamily contain two neuralized homology regions (NHRs) responsible for Neural-ligand interactions and a modified C3HC5-type RING-HC finger required for ubiquitin ligase activity. The C3HC5-type RING-HC finger is distinguished from typical C3HC4-type RING-HC finger due to the existence of the additional cysteine residue in the middle portion of the RING finger domain.

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gi 1974206313 347 CKICAENNKDVQIRPCGHL-LCREClkSWQLSKS-PTCPFCRQTI 389
Cdd:cd16647     4 CVICYERPVDTVLYRCGHMcMCYDC--ALQLKRRgGSCPICRAPI 46

RING finger, HC subclass, found in tripartite motif-containing protein 69 (TRIM69) and similar proteins; TRIM69, also known as RFP-like domain-containing protein trimless or RING finger protein 36 (RNF36), is a testis E3 ubiquitin-protein ligase that plays a specific role in apoptosis and may also play an important role in germ cell homeostasis during spermatogenesis. TRIM69 belongs to the C-IV subclass of the TRIM (tripartite motif) family of proteins that are defined by their N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as a B30.2/SPRY (SplA and ryanodine receptor) domain positioned C-terminal to the RBCC domain.

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gi 1974206313 347 CKICAENNKDVQIRPCGHLLCRECLKSW--QLSKSPTCPFCRQ 387
Cdd:cd16611     7 CPLCLDFFRDPVMLSCGHNFCQSCITGFweLQAEDTTCPECRE 49

RING finger, HC subclass, found in RING finger and transmembrane domain-containing protein 2(RNFT2); RNFT2, also known as transmembrane protein 118 (TMEM118), is a multi-pass membrane protein containing a C3HC4-type RING-HC finger. Its biological role remains unclear.

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gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCRECLKSWqLSKSPTCPFCRQTI 389
Cdd:cd16742    15 ICAICQAEFREPLILICQHVFCEECLCLW-FDRERTCPLCRSVV 57

RING finger, H2 subclass, found in RING finger protein 145 (RNF145) and similar proteins; RNF145 is an uncharacterized RING finger protein encoded by the RNF145 gene, which is expressed in T lymphocytes, and its expression is altered in acute myelomonocytic and acute promyelocytic leukemias. Although its biological function remains unclear, RNF145 shows high sequence similarity with RNF139, an endoplasmic reticulum (ER)-resident multi-transmembrane protein that functions as a potent growth suppressor in mammalian cells, inducing G2/M arrest, decreased DNA synthesis and increased apoptosis. Like RNF139, RNF145 contains a C3H2C3-type RING-H2 finger with possible E3-ubiquitin ligase activity.

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gi 1974206313 346 LCKICAENNKDVQIRPCGHLLCRECLKSWqLSKSPTCPFC 385
Cdd:cd16684     4 ICSICYQDMKSAVITPCSHFFHAGCLKKW-LYVQETCPLC 42