PDZ1 domain of human syntaxin-binding protein 4 (STXBP4), PDZ2 domain of Gallus gallus uncharacterized STXBP4 isoform X1, and related domains
PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 1 of human syntaxin-binding protein 4 (STXBP4), PDZ2 domain of Gallus gallus uncharacterized STXBP4 isoform X1, and related domains. Human STXBP4 (also known as Synip) includes a single PDZ domain, a coiled-coil domain, and a WW domain (named for its two conserved tryptophans); Gallus gallus STXBP4 isoform X1 contains 2 PDZ domains (PDZ1 and PDZ2). Human STXBP4 plays a role in the translocation of transport vesicles from the cytoplasm to the plasma membrane: insulin induces the dissociation of the STXBP4 and STX4 complex liberating STX4 to interact with Vamp2, and to form the SNARE complex thereby promoting vesicle fusion. It may also play a role in the regulation of insulin release by pancreatic beta cells after stimulation by glucose. Human STXBP4 is also known to physically associate with a prominent isoform of TP63 (deltaNp63alpha 9) whose overexpression promotes squamous cell carcinoma development, and in doing so prevents degradation of this isoform by the Cdc20-APC/C complex, Itch, and RACK1. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This STXBP4-like family domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.
Feature 1:peptide binding site [polypeptide binding site]
Evidence:
Comment:based on canonical PDZ domains with structure
Comment:PDZ domains specifically recognize and bind to short C-terminal peptide motifs, but can also recognize internal peptide motifs and certain lipids
Jiyao W et al.(2023). "The conserved domain database in 2023.",