[MAGUKs: membraneassociated guanylate kinases]

膜結合性グアニル酸キナーゼ。

【特徴】

　　・NMDA受容体を繋留する

【分類】

　　・PSD95(DLG4)
　　・PSD-93
　　・SAP97
　　・SAP102

. The MAGUKs are defined by their inclusion of PDZ, SH3 and GUK domains, although many of them also contain regions homologous of CaMKII, WW and L27 domains.[4] The GUK domain that they have is structurally very similar to that of the guanylate kinases, however it is known to be catalytically inactive as the P-Loop which binds ATP is absent. It is thought that the MAGUKs have subfunctionalized the GUK domain for their own purposes, primarily based on its ability to form protein-protein interactions with cytoskeleton proteins, microtubule/actin based machinery and molecules involved in signal transduction.

The PDZ domain which are contained in the MAGUKs in varying numbers, is replicated three times over in DLG4. PDZ domains are short peptide binding sequences commonly found at C-terminals of interacting proteins. The three copies within the gene have different binding partners, due to amino acid substitutions within the DLG4 protein and its ligands. The SH3 domain is again a protein-protein interaction domain. Its family generally bind to PXXP sites, but in MAGUKs it is known to bind to other sites as well. One of the most well known features is that it can form a intramolecular bond with the GUK domain, creating what is known as a GUK-SH3 'closed' state. The regulatory mechanisms and function are unknown but it is hypothesized that it may involve a hook region and a CaM binding region located elsewhere in the gene.