Seven in absentia protein family; The seven in absentia (sina) gene was first identified in Drosophila. The Drosophila Sina protein is essential for the determination of the R7 pathway in photoreceptor cell development: the loss of functional Sina results in the transformation of the R7 precursor cell to a non- neuronal cell type. The Sina protein contains an N-terminal RING finger domain pfam00097. Through this domain, Sina binds E2 ubiquitin-conjugating enzymes (UbcD1) Sina also interacts with Tramtrack (TTK88) via PHYL. Tramtrack is a transcriptional repressor that blocks photoreceptor determination, while PHYL down-regulates the activity of TTK88. In turn, the activity of PHYL requires the activation of the Sevenless receptor tyrosine kinase, a process essential for R7 determination. It is thought that thus Sina targets TTK88 for degradation, therefore promoting the R7 pathway. Murine and human homologs of Sina have also been identified. The human homolog Siah-1 also binds E2 enzymes (UbcH5) and through a series of physical interactions, targets beta-catenin for ubiquitin degradation. Siah-1 expression is enhanced by p53, itself promoted by DNA damage. Thus this pathway links DNA damage to beta-catenin degradation. Sina proteins, therefore, physically interact with a variety of proteins. The N-terminal RING finger domain that binds ubiquitin conjugating enzymes is described in pfam00097, and does not form part of the alignment for this family. The remainder C-terminal part is involved in interactions with other proteins, and is included in this alignment. In addition to the Drosophila protein and mammalian homologs, whose similarity was noted previously, this family also includes putative homologs from Caenorhabditis elegans, Arabidopsis thaliana.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 887844646   35 IRNLAMEKVANSVLFPCKYASSGCEVTLPHTEKADHEELCEFRPYSCPCPGASCKWQGSLDAVMPHLMHQHKSITTLQGE 114
Cdd:pfam03145   1 IRNLALEKVAESLLFPCKYASSGCSETLPYTEKADHEERCEFRPYSCPCPGSSCTWQGSLDAVMPHLMDDHKKVTTLQGE 80

                          90
                  ....*....|....*....
gi 887844646  115 DIVFLATDIN-LPGAVDWV 132
Cdd:pfam03145  81 DFVFLATDINkLDGAVDWV 99

Seven in absentia protein family; The seven in absentia (sina) gene was first identified in Drosophila. The Drosophila Sina protein is essential for the determination of the R7 pathway in photoreceptor cell development: the loss of functional Sina results in the transformation of the R7 precursor cell to a non- neuronal cell type. The Sina protein contains an N-terminal RING finger domain pfam00097. Through this domain, Sina binds E2 ubiquitin-conjugating enzymes (UbcD1) Sina also interacts with Tramtrack (TTK88) via PHYL. Tramtrack is a transcriptional repressor that blocks photoreceptor determination, while PHYL down-regulates the activity of TTK88. In turn, the activity of PHYL requires the activation of the Sevenless receptor tyrosine kinase, a process essential for R7 determination. It is thought that thus Sina targets TTK88 for degradation, therefore promoting the R7 pathway. Murine and human homologs of Sina have also been identified. The human homolog Siah-1 also binds E2 enzymes (UbcH5) and through a series of physical interactions, targets beta-catenin for ubiquitin degradation. Siah-1 expression is enhanced by p53, itself promoted by DNA damage. Thus this pathway links DNA damage to beta-catenin degradation. Sina proteins, therefore, physically interact with a variety of proteins. The N-terminal RING finger domain that binds ubiquitin conjugating enzymes is described in pfam00097, and does not form part of the alignment for this family. The remainder C-terminal part is involved in interactions with other proteins, and is included in this alignment. In addition to the Drosophila protein and mammalian homologs, whose similarity was noted previously, this family also includes putative homologs from Caenorhabditis elegans, Arabidopsis thaliana.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 887844646   35 IRNLAMEKVANSVLFPCKYASSGCEVTLPHTEKADHEELCEFRPYSCPCPGASCKWQGSLDAVMPHLMHQHKSITTLQGE 114
Cdd:pfam03145   1 IRNLALEKVAESLLFPCKYASSGCSETLPYTEKADHEERCEFRPYSCPCPGSSCTWQGSLDAVMPHLMDDHKKVTTLQGE 80

                          90
                  ....*....|....*....
gi 887844646  115 DIVFLATDIN-LPGAVDWV 132
Cdd:pfam03145  81 DFVFLATDINkLDGAVDWV 99

Seven in absentia (Sina) protein family, C-terminal substrate binding domain; composed of the Drosophila Sina protein, the mammalian Sina homolog (Siah), the plant protein SINAT5, and similar proteins. Sina, Siah and SINAT5 are RING-containing proteins that function as E3 ubiquitin ligases, acting either as single proteins or as a part of multiprotein complexes. Sina is expressed in many cells in the developing eye but is essential specifically for R7 photoreceptor cell development. Sina cooperates with Phyllopod (Phyl), Ebi and the E2 ubiquitin-conjugating enzyme Ubcd1 to catalyze the ubiquitination and subsequent degradation of Tramtrack (Ttk88); Ttk88 is a transcriptional repressor that blocks photoreceptor differentiation. Similarly, the mammalian homologue Siah1 cooperates with SIP (Siah-interacting protein), Ebi and the adaptor protein Skp1, to target beta-catenin for ubiquitination and degradation via a p53-dependent mechanism. SINAT5 targets NAC1 for ubiquitin-mediated degradation resulting in the downregulation of auxin, a hormone that controls many aspects of plant development. Other targets of Sina family proteins include c-Myb, synaptophysin, group 1 glutamate receptors, promyelocytic leukemia protein, alpha-synuclein, synphilin-1 and alpha-ketoglutarate dehydrogenase, among others. Sina proteins also bind proteins that are not targets for ubiquitination such as Phyl, adenomatous polyposis coli, VAV, BAG-1 and Dab-1. Siah binds to a consensus motif, PXAXVXP, which is present in Siah-binding proteins. Siah is a dimeric protein consisting of an N-terminal RING domain, two zinc finger motifs and a C-terminal substrate-binding domain (SBD); this SBD contains an eight-stranded antiparallel beta-sandwich fold similar to the MATH (meprin and TRAF-C homology) domain.

                         10        20
                 ....*....|....*....|....*
gi 887844646 108 ITTLQGEDIVFLATDINLPGAVDWV 132
Cdd:cd03829    1 VTTLQGEDIVFLATDINLPGATDWV 25

Seven in absentia protein family; The seven in absentia (sina) gene was first identified in Drosophila. The Drosophila Sina protein is essential for the determination of the R7 pathway in photoreceptor cell development: the loss of functional Sina results in the transformation of the R7 precursor cell to a non- neuronal cell type. The Sina protein contains an N-terminal RING finger domain pfam00097. Through this domain, Sina binds E2 ubiquitin-conjugating enzymes (UbcD1) Sina also interacts with Tramtrack (TTK88) via PHYL. Tramtrack is a transcriptional repressor that blocks photoreceptor determination, while PHYL down-regulates the activity of TTK88. In turn, the activity of PHYL requires the activation of the Sevenless receptor tyrosine kinase, a process essential for R7 determination. It is thought that thus Sina targets TTK88 for degradation, therefore promoting the R7 pathway. Murine and human homologs of Sina have also been identified. The human homolog Siah-1 also binds E2 enzymes (UbcH5) and through a series of physical interactions, targets beta-catenin for ubiquitin degradation. Siah-1 expression is enhanced by p53, itself promoted by DNA damage. Thus this pathway links DNA damage to beta-catenin degradation. Sina proteins, therefore, physically interact with a variety of proteins. The N-terminal RING finger domain that binds ubiquitin conjugating enzymes is described in pfam00097, and does not form part of the alignment for this family. The remainder C-terminal part is involved in interactions with other proteins, and is included in this alignment. In addition to the Drosophila protein and mammalian homologs, whose similarity was noted previously, this family also includes putative homologs from Caenorhabditis elegans, Arabidopsis thaliana.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 887844646   35 IRNLAMEKVANSVLFPCKYASSGCEVTLPHTEKADHEELCEFRPYSCPCPGASCKWQGSLDAVMPHLMHQHKSITTLQGE 114
Cdd:pfam03145   1 IRNLALEKVAESLLFPCKYASSGCSETLPYTEKADHEERCEFRPYSCPCPGSSCTWQGSLDAVMPHLMDDHKKVTTLQGE 80

                          90
                  ....*....|....*....
gi 887844646  115 DIVFLATDIN-LPGAVDWV 132
Cdd:pfam03145  81 DFVFLATDINkLDGAVDWV 99

RING finger, HC subclass, found in seven in absentia homolog 1 (SIAH1) and similar proteins; SIAH1, also known as Siah-1a, is an inducible E3 ubiquitin-protein ligase that contributes to proteasome-mediated degradation of multiple targets in numerous cellular processes including apoptosis, tumor suppression, cell cycle, axon guidance, transcription regulation, and tumor necrosis factor signaling. SIAH1 functions as a scaffolding protein and interacts with a variety of different substrates for ubiquitination and subsequent degradation. It regulates the oncoprotein p34SEI-1 polyubiquitination and its subsequent degradation in a p53-dependent manner, which mediates p53 preferential vitamin C cytotoxicity. It targets the nonreceptor tyrosine kinase activated Cdc42-associated kinase 1 (ACK1), a valid target in cancer therapy, for ubiquitinylation and proteasomal degradation. It also interacts with KLF10 and targets it for degradation. The CDK2 phosphorylation-mediated KLF10 dissociation from SIAH1 is linked to cell cycle progression. Moreover, SIAH1 is downregulated and associated with apoptosis and invasion in human breast cancer. It targets TAp73, a homolog of the tumor suppressor p53, for degradation. It is suppressed by hypoxia-inducible factor 1-alpha (HIF-1alpha) under hypoxic conditions to regulate TAp73 levels. It also promotes the migration and invasion of human glioma cells by regulating HIF-1alpha signaling under hypoxia. Furthermore, SIAH1 forms a protein complex with glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The apoptosis signal-regulating kinase 1 (ASK1) functions as an activator of the GAPDH-Siah1 stress-signaling cascade. It also plays an important role in ethanol-induced apoptosis in neural crest cells (NCCs). SIAH1 contains an N-terminal C3HC4-type RING-HC finger, two zinc-finger subdomains, and a C-terminal tumor necrosis factor (TNF) receptor associated factor (TRAF)-like substrate-binding domain (SBD) responsible for dimer formation.

                         10        20        30
                 ....*....|....*....|....*....|.
gi 887844646   1 VLPPILQCQSGHLVCSNCRPKLTCCPTCRGP 31
Cdd:cd16751   15 VLPPILQCQSGHLVCSNCRPKLTCCPTCRGP 45

RING finger, HC subclass, found in Drosophila melanogaster protein Seven-in-Absentia (sina) and its homologs; This subfamily includes the Drosophila melanogaster protein Seven-in-Absentia (sina), its mammalian orthologs, SIAH1 and SIAH2, plant SINA-related proteins, and similar proteins. Sina plays an important role in the phyllopod-dependent degradation of the transcriptional repressor tramtrack to allow the formation of the R7 photoreceptor in the developing eye of Drosophila melanogaster. Both SIAH1 and SIAH2 are E3 ubiquitin-protein ligases, mediating the ubiquitinylation and subsequent proteasomal degradation of biologically important target proteins that regulate general functions, such as cell cycle control, apoptosis, and DNA repair. They are inducible by the tumor suppressor and transcription factor p53. SIAH2 can also be regulated by sex hormones and cytokine signaling. Moreover, they share high sequence similarity, but possess contrary roles in cancer, with SIAH1 more often acting as a tumor suppressor while SIAH2 functions as a proto-oncogene. Plant SINAT1-5 are putative E3 ubiquitin ligases involved in the regulation of stress responses. All subfamily members possess two characteristic domains, an N-terminal C3HC4-type RING-HC finger and a C-terminal tumor necrosis factor (TNF) receptor associated factor (TRAF)-like substrate-binding domain (SBD).

                         10        20        30
                 ....*....|....*....|....*....|
gi 887844646   1 VLPPILQCQSGHLVCSNCRPKLT-CCPTCR 29
Cdd:cd16571   10 LLPPIYQCSNGHLLCSSCRSKLTnKCPTCR 39