Plays a role in rod outer segment (ROS) morphogenesis (By similarity). May play a role with PRPH2 in the maintenance of the structure of ROS curved disks (PubMed:24196967). Plays a role in the organization of the ROS and maintenance of ROS disk diameter (By similarity). Involved in the maintenance of the retina outer nuclear layer (By similarity). Homodimer; disulfide-linked (PubMed:1610568). Forms a homotetramer (PubMed:10681511). Forms a heterotetramer with PRPH2 (PubMed:1610568, PubMed:10681511, PubMed:24196967). Homotetramer and heterotetramer core complexes go on to form higher order complexes by formation of intermolecular disulfide bonds (PubMed:10681511). Interacts with STX3 (By similarity). Interacts with SNAP25 (By similarity). Retina photoreceptor (at protein level) (PubMed:8603840, PubMed:10681511). In rim region of ROS disks (at protein level) (PubMed:8603840, PubMed:10681511). May be involved in mammalian retinopathies (PubMed:8603840). Belongs to the PRPH2/ROM1 family.