A segment corresponding to amino acids Val170-Arg182 of bovine arrestin is capable of binding to phosphorylated rhodopsin.
In retinal rods, photoexcited rhodopsin (R*) is inactivated upon phosphorylation by rhodopsin kinase and the subsequent binding of arrestin. We have studied the structural role of a cationic region of bovine arrestin (Val170-Arg182) using anti-peptide IgGs specifically recognizing this segment and the corresponding oligopeptide. Our results clearly indicate that amino acids Val170-Arg182 are shielded within the arrestin-rhodopsin-complex and very likely belong to a binding domain of arrestin for phosphorylated R*. The purified anti-peptide IgGs strongly reacted with isolated arrestin but did not recognize arrestin when bound to phosphorylated R*. In agreement with these experiments, the oligopeptide Val170-Arg182 was found to compete with arrestin for binding to phosphorylated R*. Increasing concentrations of this peptide caused an oligomerization of phosphorylated rhodopsin when illuminated by white light as well as in the dark. Unphosphorylated rhodopsin did not oligomerize up to a 400-fold molar ratio of peptide/rhodopsin. Limited proteolysis of the phosphorylated carboxy-terminus of rhodopsin with endoproteinase Asp-N caused a significant decrease in the peptide-induced formation of oligomers. Therefore, Val170-Arg182 of bovine arrestin probably interacts with the phosphorylated carboxy-terminus of rhodopsin. The data presented support the proposal of Palczewski et al. (1991c) considering the region Lys163-Arg182 in bovine arrestin to be a possible binding domain for phosphorylated R*.
Max-Volmer-Institut für Biophysikalische und Physikalische Chemie, Technische Universität Berlin, Germany.
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Irrgang
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D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D000941:Antigens / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D019393:Arrestin; D001667:Binding, Competitive; D002417:Cattle; D005136:Eye Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D012243:Rhodopsin / Q000378:metabolism*; D014633:Valine / Q000378:metabolism*
D000906:Antibodies; D000941:Antigens; D019393:Arrestin; D005136:Eye Proteins; D012243:Rhodopsin; D001120:Arginine; D014633:Valine