SAG (S-Antigen Visual Arrestin) is a Protein Coding gene. Diseases associated with SAG include Oguchi Disease-1 and Retinitis Pigmentosa 47. Among its related pathways are Phototransduction and Visual Cycle in Retinal Rods. S-arrestin, also known as S-antigen, is a major soluble photoreceptor protein that is involved in desensitization of the photoactivated transduction cascade. It is expressed in the retina and the pineal gland and inhibits coupling of rhodopsin to transducin in vitro. Additionally, S-arrestin is highly antigenic, and is capable of inducing experimental autoimmune uveoretinitis. Mutations in SAG have been associated with Oguchi disease, a rare autosomal recessive form of night blindness.