SAG

Members of arrestin/beta-arrestin protein family are thought to participate in agonist-mediated desensitization of G-protein-coupled receptors and cause specific dampening of cellular responses to stimuli such as hormones, neurotransmitters, or sensory signals. 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 this gene have been associated with Oguchi disease, a rare autosomal recessive form of night blindness.

S-antigen visual arrestin

Binds to photoactivated, phosphorylated RHO and terminates RHO signaling via G-proteins by competing with G-proteins for the same binding site on RHO (By similarity).
May play a role in preventing light-dependent degeneration of retinal photoreceptor cells (PubMed:9565049).

Biological Process cell surface receptor signaling pathwayManual Assertion Based On ExperimentTAS:ProtInc
Biological Process G protein-coupled receptor internalizationManual Assertion Based On ExperimentIBA:GO_Central
Biological Process rhodopsin mediated signaling pathwayManual Assertion Based On ExperimentTAS:ProtInc

Cell projection, cilium, photoreceptor outer segment
Membrane
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 (PubMed:3720866).

Night blindness, congenital stationary, Oguchi type 1 (CSNBO1):
A non-progressive retinal disorder characterized by impaired night vision, often associated with nystagmus and myopia. Congenital stationary night blindness Oguchi type is an autosomal recessive form associated with fundus discoloration and abnormally slow dark adaptation.
Retinitis pigmentosa 47 (RP47):
A retinal dystrophy belonging to the group of pigmentary retinopathies. Retinitis pigmentosa is characterized by retinal pigment deposits visible on fundus examination and primary loss of rod photoreceptor cells followed by secondary loss of cone photoreceptors. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well.