Plays a role in rod outer segment (ROS) morphogenesis (PubMed:10802659). May play a role with PRPH2 in the maintenance of the structure of ROS curved disks (By similarity). Plays a role in the organization of the ROS and maintenance of ROS disk diameter (PubMed:10802659). Involved in the maintenance of the retina outer nuclear layer (PubMed:10802659). Homodimer; disulfide-linked (By similarity). Forms a homotetramer (By similarity). Forms a heterotetramer with PRPH2 (PubMed:26406599, PubMed:29961824). Homotetramer and heterotetramer core complexes go on to form higher order complexes by formation of intermolecular disulfide bonds (By similarity). Interacts with STX3 isoform 3B (PubMed:26406599). Interacts with SNAP25 (PubMed:26406599). Expressed in the retina (at protein level). Knockout mice are viable, fertile and grossly phenotypically normal (PubMed:10802659). 50% reduction in maximal rod photoreceptor response at 9 months of age (PubMed:10802659). Progressive thinning of the retinal outer nuclear layer becomes evident at 1 month of age (PubMed:10802659). Evidence of rod photoreceptor degeneration, shortened rod outer segment (ROS) length, increased ROS disk diameter, and progressive disorganization of the ROS at 1 month of age, leading to near-complete loss of organization by 2 months of age, however organization returns to near normal levels by 4 months of age (PubMed:10802659). Rod photoreceptors progressively die by apoptosis (PubMed:10802659). Knockout does not affect localization of Prph2 or Abca4 to ROS disk rims (PubMed:10802659). Belongs to the PRPH2/ROM1 family.