MPP7 is a scaffolding protein that binds to DLG1 and promotes tight junction formation and epithelial cell polarity [, ]. Mutations in the MPP7 gene may be associated with the pathogenesis of diabetes []and extreme bone mineral density []. It is one of seven vertebrate homologues of the Drosophila Stardust protein, which is required in establishing cell polarity, and it contains two L27 domains followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK) []. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. This entry represents the SH3 domain of MPP7.
