Phosducin (Phd)-like family, Viral inhibitor of apoptosis (IAP)-associated factor (VIAF) subfamily; VIAF is a Phd-like protein that functions in caspase activation during apoptosis. It was identified as an IAP binding protein through a screen of a human B-cell library using a prototype IAP. VIAF lacks a consensus IAP binding motif and while it does not function as an IAP antagonist, it still plays a regulatory role in the complete activation of caspases. VIAF itself is a substrate for IAP-mediated ubiquitination, suggesting that it may be a target of IAPs in the prevention of cell death. The similarity of VIAF to Phd points to a potential role distinct from apoptosis regulation. Phd functions as a cytosolic regulator of G protein by specifically binding to G protein betagamma (Gbg)-subunits. The C-terminal domain of Phd adopts a thioredoxin fold, but it does not contain a CXXC motif. Phd interacts with G protein beta mostly through the N-terminal helical domain.
Feature 1:putative G protein beta interface [polypeptide binding site]
Evidence:
Comment:based on structure of phosducin and transducin complex
Comment:Most of the binding energy comes from the N-terminal helical domain of phosducin with a lesser contribution from the C-terminal TRX-like domain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",