PDZ domain 2 of the full-length isoform of whirlin and related domains
PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 2 of the full-length isoform of whirlin and related domains. Whirlin is an essential protein for developmental pathways in photoreceptor cells of the retina and hair cells of the inner ear. The full-length whirlin isoform has two harmonin N-like domains, three PDZ domains, a proline-rich region, and a PDZ-binding motif. Whirlin isoforms may form different complexes at the periciliary membrane complex (PMC) in photoreceptors, and the stereociliary tip and base in inner ear hair cells. It interacts with ADGRV1 and usherin at the PMC; with SANS and RpgrORF15 at the connecting cilium in photoreceptors; with EPS8, MYO15A, p55, and CASK proteins at the stereociliary tip of inner ear hair cells; and with ADGRV1, usherin, and PDZD7 at the stereociliary base in inner ear hair cells. Mutations in the gene encoding whirlin (WHRN; also known as USH2D and DFNB31), have been found to cause either USH2 subtype (USH2D) or autosomal recessive non-syndromic deafness type 31 (DFNB31). Whirlin is the key protein in the USH2 complex (whirlin, usherin and GPR98) which recruits other USH2 causative proteins at the periciliary membrane in photoreceptors and the ankle link of the stereocilia in hair cells. Whirlin's interaction with espin, another stereociliary protein, may be important for the architecture of the USH2 complex. 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 whirlin family PDZ2 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.",