Identification of visual arrestin (S-antigen) in retinal pigmented epithelial cells

Purpose. Inactivation of photolyzed rhodopsin requires phosphorylation of t his receptor and binding of the 48 kDa regulatory protein arrestin (S-antig en). Arrestin is also to cause an autoimmun disease, uveoretinits, that res embles uveitis in humans. In this study we demonstrate the presence of visu al arrestin in retinal pigment epithelial cells (RPE) in culture. Methods. Bovine RPE were isolated. Mouse and rat monoclonal and rabbit poly clonal antibodies against visual arrestin, and a synthetic peptide "GFLGELT SSEVATEVPFRLM" (a pathogenic sequence corresponding to residues 340 to 359 of human visual arrestin), and rabbit polyclonal antibody against the speci fic peptide "EDPDTAKESFQ" for bovine visual arrestin were used to detect ar restin in RPE cells. Using visual arrestin specific primer, RT-PCR of RNA f rom RPE was performed. Results. By western blots analysis a 48 kDa protein, corresponding to visua l arrestin was detected with both mAb and polyclonal antibodies in extracts of RPE cells. RT-PCR analysis of RNA from RPE cells confirmed the presence of arrestin mRNA of predicted 377 bp and exhibited 100% homology with visu al arrestin 48 kDa. Conclusion. Visual arrestin proteins present in RPE may be involved in the desensitization of G-protein-coupled receptors in RPE cells and in arrestin uveopathogenesis.