Binds to photoactivated, phosphorylated RHO and terminates RHO signaling via G-proteins by competing with G-proteins for the same binding site on RHO. May play a role in preventing light-dependent degeneration of retinal photoreceptor cells. Monomer. Homodimer. Homotetramer. Interacts with RHO (via the phosphorylated C-terminus). Highly expressed in photoreceptor outer segments in light-exposed retina. Evenly distributed throughout rod photoreceptor cells in dark-adapted retina (By similarity). Predominantly dectected at the proximal region of photoreceptor outer segments, near disk membranes. Retina and pineal gland. The C-terminus interferes with binding to non-phosphorylated RHO. Interaction with phosphorylated RHO triggers displacement of the C-terminus and leads to a conformation change that mediates high-affinity RHO binding. Belongs to the arrestin family.