SINA/Siah family proteins represent mammalian homologs of the Drosophila SINA
(seven in absentia) protein. SINA is required for R7 photoreceptor cell
differentiation within the sevenless pathway . Members of this family are
E3 ubiquitin ligases that regulate ubiquitination and protein degradation.
Siahs are known to recognize several target proteins including Deleted in
Colorectal Cancer (DCC), synaptophysin and Numb and promote their degradation
SINA/Siah sequences are highly conserved from plants to mammals. Whereas the N
terminus and RING domain of Siah bind E2 proteins, the C terminus can be
considered as a substrate- and cofactor-interaction domain (substrate-binding
domain, SBD) that interacts with a number of proteins, some of which are
degraded . The SBD domain displays some sequence similarities with the
C-terminal region of TRAF proteins. It contains a cysteine-rich region, the
SIAH-type zinc finger, with eight totally conserved Cys and His residues that
coordinate two zinc atoms .
The crystal structure of SIAH-type zinc finger has been solved (see
<PDB:1K2F>) . It folds in two subdomains, each one binding one zinc atom
and consisting of two β-strands and an α helice.
The profile we developed covers the entire SIAH-type zinc finger.
February 2005 / First entry.
PROSITE method (with tools and information) covered by this documentation:
Carthew R.W. Rubin G.M.
seven in absentia, a gene required for specification of R7 cell fate in the Drosophila eye.
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