This gene encodes a member of the membrane-associated guanylate kinase (MAGUK) protein family, with an N-terminal PDZ domain, a central src homology 3 region (SH3), and a C-terminal guanylate kinase-like (GUK) domain. The protein is localized to the outer limiting membrane in the retina, and is thought to function in photoreceptor polarity and the organization of specialized intercellular junctions. Alternatively spliced transcript variants have been described, but their biological validity has not been determined. [provided by RefSeq, Jul 2008].