May play a role in an as yet undefined retina-specific signal transduction. Could bind to photoactivated-phosphorylated red/green opsins. Homodimer; disulfide-linked in response to retinal illumination (PubMed:25772009). Interacts with CXCR4; the interaction is dependent on the C-terminal phosphorylation of CXCR4 and modulates the calcium ion mobilization activity of CXCR4 (By similarity). Expressed in cone photoreceptors in the retina (at protein level). Belongs to the arrestin family.