The protein encoded by this gene is a member of the p55 Stardust family of membrane-associated guanylate kinase (MAGUK) proteins, which function in the establishment of epithelial cell polarity. This family member forms a complex with the polarity protein DLG1 (discs, large homolog 1) and facilitates epithelial cell polarity and tight junction formation. Polymorphisms in this gene are associated with variations in site-specific bone mineral density (BMD). Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2015].