U-box domain, a modified RING finger, found in Arabidopsis plant U-box proteins (AtPUB) and similar proteins; The plant PUB proteins, also known as U-box domain-containing proteins, are much more numerous in Arabidopsis which has 62 in comparison with the typical 6 in most animals. The majority of AtPUBs in this subfamily are known as ARM domain-containing PUB proteins, containing a C-terminally-located, tandem ARM (armadillo) repeat protein-interaction region in addition to the U-box domain. They have been implicated in the regulation of cell death and defense. They also play important roles in other plant-specific pathways, such as controlling both self-incompatibility and pseudo-self-incompatibility, as well as acting in abiotic stress. A subgroup of ARM domain-containing PUB proteins harbors a plant-specific U-box N-terminal domain.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 723680256 261 PDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSL 313
Cdd:cd16664    1 PEEFICPISLELMKDPVILATGQTYERAAIEKWLDSGNNTCPITGQPLTHTDL 53

U-box domain, a modified RING finger, found in Arabidopsis plant U-box proteins (AtPUB) and similar proteins; The plant PUB proteins, also known as U-box domain-containing proteins, are much more numerous in Arabidopsis which has 62 in comparison with the typical 6 in most animals. The majority of AtPUBs in this subfamily are known as ARM domain-containing PUB proteins, containing a C-terminally-located, tandem ARM (armadillo) repeat protein-interaction region in addition to the U-box domain. They have been implicated in the regulation of cell death and defense. They also play important roles in other plant-specific pathways, such as controlling both self-incompatibility and pseudo-self-incompatibility, as well as acting in abiotic stress. A subgroup of ARM domain-containing PUB proteins harbors a plant-specific U-box N-terminal domain.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 723680256 261 PDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSL 313
Cdd:cd16664    1 PEEFICPISLELMKDPVILATGQTYERAAIEKWLDSGNNTCPITGQPLTHTDL 53

U-box domain; The U-box is a domain of ~70 amino acids that is present in proteins from yeast to human. It consists of the beta-beta-alpha-beta-alpha- fold typical of U-box and RING domains. The central alpha helix is flanked by two prominent surface-exposed loop regions. This domain is one class of E3 ligases, involved in the ubiquitination process. This domain is related to the Ring finger pfam00097 but lacks the zinc binding residues.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 723680256  261 PDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSLTPNHTMKDLISRWSATH 330
Cdd:pfam04564   2 PDEFLDPITFELMTDPVILPSGITYDRSTIERHLLSVDPTDPFTREPLTHDQLIPNLELKAKIDAWLEEK 71

U-box domain, a modified RING finger, found in Arabidopsis plant U-box proteins (AtPUB) and similar proteins; The plant PUB proteins, also known as U-box domain-containing proteins, are much more numerous in Arabidopsis which has 62 in comparison with the typical 6 in most animals. The majority of AtPUBs in this subfamily are known as ARM domain-containing PUB proteins, containing a C-terminally-located, tandem ARM (armadillo) repeat protein-interaction region in addition to the U-box domain. They have been implicated in the regulation of cell death and defense. They also play important roles in other plant-specific pathways, such as controlling both self-incompatibility and pseudo-self-incompatibility, as well as acting in abiotic stress. A subgroup of ARM domain-containing PUB proteins harbors a plant-specific U-box N-terminal domain.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 723680256 261 PDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSL 313
Cdd:cd16664    1 PEEFICPISLELMKDPVILATGQTYERAAIEKWLDSGNNTCPITGQPLTHTDL 53

U-box domain; The U-box is a domain of ~70 amino acids that is present in proteins from yeast to human. It consists of the beta-beta-alpha-beta-alpha- fold typical of U-box and RING domains. The central alpha helix is flanked by two prominent surface-exposed loop regions. This domain is one class of E3 ligases, involved in the ubiquitination process. This domain is related to the Ring finger pfam00097 but lacks the zinc binding residues.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 723680256  261 PDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSLTPNHTMKDLISRWSATH 330
Cdd:pfam04564   2 PDEFLDPITFELMTDPVILPSGITYDRSTIERHLLSVDPTDPFTREPLTHDQLIPNLELKAKIDAWLEEK 71

U-box domain, a modified RING finger, found in carboxyl terminus of HSP70-interacting protein (CHIP) and similar proteins; CHIP, also known as STIP1 homology and U box-containing protein 1 (STUB1), CLL-associated antigen KW-8, or Antigen NY-CO-7, is a multifunctional protein that functions both as a co-chaperone and an E3 ubiquitin-protein ligase. It couples protein folding and proteasome mediated degradation by interacting with heat shock proteins (e.g. HSC70) and ubiquitinating their misfolded client proteins, thereby targeting them for proteasomal degradation. It is also important for cellular differentiation and survival (or apoptosis), as well as susceptibility to stress. It targets a wide range of proteins, such as expanded ataxin-1, ataxin-3, huntingtin, and androgen receptor, which play roles in glucocorticoid response, tau degradation, and both p53 and cAMP signaling. CHIP contains an N-terminal tetratricopeptide repeat (TPR) domain responsible for protein-protein interaction, a highly charged middle coiled-coil (CC), and a C-terminal RING-like U-box domain acting as an ubiquitin ligase.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 723680256 260 PPDEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSLTPNHTMKDLISRW 326
Cdd:cd16654    1 VPDYLCCKISFELMRDPVITPSGITYERKDIEEHLQRVGHFDPITREPLTQDQLIPNLALKEAIEAF 67

first U-box domain, a modified RING finger, found in Legionella pneumophila U-box protein LubX and similar proteins; LubX, also called RING-type E3 ubiquitin transferase LubX, is part of the large arsenal of effectors in Legionella pneumophila that are translocated into the host cytosol during infection. LubX acts as an E3 ubiquitin-protein ligase (EC 2.3.2.27) that interferes with the host's ubiquitination pathway. LubX contains two RING-like U-box domains. U-box 1 is critical to the ubiquitin ligase activity, and U-box 2 mediates interaction with host target. This model corresponds to the first one.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 723680256 264 FKCPLSLRLMYEPVVIASGRTYERFQILKWFaEGNDTCPTTRRKLANLSLTPN 316
Cdd:cd23149    1 FTCPITSGFMEDPVITPSGFSYERSAIERWL-ETKPEDPQTREPLTAKDLQPN 52

SPL-RING finger found in E3 SUMO-protein ligase NSE2 and similar proteins; NSE2, also known as MMS21 homolog (MMS21) or non-structural maintenance of chromosomes element 2 homolog (Non-SMC element 2 homolog, NSMCE2), is an autosumoylating small ubiquitin-like modifier (SUMO) ligase required for the response to DNA damage. It regulates sumoylation and nuclear-to-cytoplasmic translocation of skeletal and heart muscle-specific variant of the alpha subunit of nascent polypeptide associated complex (skNAC)-Smyd1 in myogenesis. It is also required for resisting extrinsically induced genotoxic stress. Moreover, NSE2 together with its partner proteins SMC6 and SMC5 form a tight subcomplex of the structural maintenance of chromosomes SMC5-6 complex, which includes another two subcomplexes, NSE1-NSE3-NSE4 and NSE5-NSE6. SMC6 and NSE3 are sumoylated in an NSE2-dependent manner, but SMC5 and NSE1 are not. NSE2-dependent E3 SUMO ligase activity is required for efficient DNA repair, but not for SMC5-6 complex stability. NSE2 contains a RING variant known as a Siz/PIAS (protein inhibitor of activated signal transducer and activator of transcription)-like RING (SPL-RING) finger that is likely shared by the SP-RING type SUMO E3 ligases, such as PIAS family proteins. The SPL-RING finger is a variant of the RING finger, which lacks the second, fifth, and sixth zinc-binding residues of the consensus C3H2C3-/C3HC4-type RING fingers. It harbors only one Zn binding site and is required for the sumoylating activity.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 723680256 264 FKCPLSLRLMYEPVV-IASGRTYERFQILKWFAEGNDT--CPTT--RRKLANLSLTPNHTMKDLISR 325
Cdd:cd16651    1 LKCPITQQLMVDPVRnKKCGHTYEKAAILQYLQSRKKKakCPVAgcRNTVSKSDLVPDPELKRRIER 67

RING finger, HC subclass, found in tripartite motif-containing protein TRIM21 and similar proteins; TRIM21, also known as 52 kDa Ro protein, 52 kDa ribonucleoprotein autoantigen Ro/SS-A, Ro(SS-A), RING finger protein 81 (RNF81), or Sjoegren syndrome type A antigen (SS-A), is a ubiquitously expressed E3 ubiquitin-protein ligase and a high affinity antibody receptor uniquely expressed in the cytosol of mammalian cells. As a cytosolic Fc receptor, TRIM21 binds the Fc of virus-associated antibodies and targets the complex in the cytosol for proteasomal degradation in a process known as antibody-dependent intracellular neutralization (ADIN), and provides an intracellular immune response to protect host defense against pathogen infection. It shows remarkably broad isotype specificity as it does not only bind IgG, but also IgM and IgA. Moreover, TRIM21 promotes the cytosolic DNA sensor cGAS and the cytosolic RNA sensor RIG-I sensing of viral genomes during infection by antibody-opsonized virus. It stimulates inflammatory signaling and activates innate transcription factors, such as nuclear factor-kappaB (NF-kappaB). TRIM21 also plays an essential role in p62-regulated redox homeostasis, suggesting it may be a viable target for treating pathological conditions resulting from oxidative damage. Furthermore, TRIM21 may have implications for various autoimmune diseases associated with uncontrolled antiviral signaling through the regulation of Nmi-IFI35 complex-mediated inhibition of innate antiviral response. TRIM21 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.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 723680256 262 DEFKCPLSLRLMYEPVVIASGRTYERFQILKWFAEGNDTCPTTRRKLANLSLTPNHTMKDLI 323
Cdd:cd16596    8 EEVTCPICLDPFVEPVSIECGHSFCQECISQVGKGGGSVCPVCRQRFLLKNLRPNRQLANMV 69