May play a role in retinal photoreceptors development. May interact with GRIA2 (By similarity). Interacts with MPDZ. Forms a complex with CRB1 and PALS1. Interacts with FASLG (By similarity). Localized at photoreceptor synaptic terminals in retina. Localized in rod and cone photoreceptors at the plasma membrane and at membranes of intracellular vesicles around the subapical region (SAR) and adherens junction, and in the outer plexiform layer (OPL). Detected in the retina (at protein level). Highly enriched in the retina where it is mainly expressed by rod photoreceptors; detected in the inner segment of the photoreceptor layer and in the outer nuclear layer. Also detected at much lower levels in pineal gland, cerebellum, cortex, hippocampus, olfactory bulb, heart, liver and spleen. Expressed in the CA1-CA3 regions of pyramidal cell layers and in the granule cell layer of dentate gyrus in the hippocampus. In the cerebellum, expressed in Purkinje cells and throughout the granule cell layer. In the olfactory bulb, expressed in mitral cells. Expressed postnatally in the retina. The expression in the retina coincides with one of the photoreceptor specific genes. Expressed in forebrain of 9.5 dpc embryos and in whole brain of 11.5 dpc embryos. Belongs to the MAGUK family. Frameshifts and sequencing errors.