PDZ domain 3 of partitioning defective 3 (Par3), and related domains
PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 3 of Par3 (or PAR3 or Par-3, also known as Atypical PKC isotype-specific-interacting protein, ASIP, Drosophila Bazooka) and related domains. Par3 is a scaffold protein involved in organizing cell polarity across animals. Par3 binds numerous molecules both for its recruitment to one pole of the cell and for downstream contributions to polarized cell function. It regulates cell polarity by targeting the Par complex proteins Par6 and atypical protein kinase C (aPKC) to specific cortical sites. Physical interactions between Par-3 and the Par complex include Par3 PDZ domain 1 binding to the Par6 PDZ domain, Par3 PDZ domain 1 and PDZ domain 3 binding the Par6's PDZ-binding motif, and an interaction with an undefined region of aPKC that requires both Par3 PDZ2 and PDZ3. The PDZ domains of Par3 have also been implicated as potential phosphoinositide signaling integrators, since its second PDZ domain binds to phosphoinositides, and the third PDZ interacts with phosphoinositide phosphatase PTEN. 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 Par3 family PDZ3 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
Structure:2K20; PDZ domain 3 of Rattus norvegicus Par-3 binds phosphoinositide phosphatase PTEN peptide, contacts at 4A
Comment:Par-3 PDZ domain 3 binds to PTEN with two discrete binding sites: a canonical PDZ-ligand interaction site and a distal, opposite charge-charge interaction site. This distinct target recognition mechanism confers the interaction specificity of the Par3-PTEN complex.
Jiyao W et al.(2023). "The conserved domain database in 2023.",