title: Arrestin-rhodopsin interaction. Multi-site binding delineated by peptide inhibition.
abstract: Visual arrestin modulates the intracellular response of retinal rod cells to light by specifically binding to the phosphorylated light-activated form of the photoreceptor rhodopsin (P-Rh*). In order to characterize the molecular interaction between rhodopsin and arrestin, we have studied the ability of synthetic peptides from the proposed cytoplasmic loops of rhodopsin to inhibit arrestin binding. A third cytoplasmic loop peptide competed most effectively for arrestin binding to P-Rh*, exhibiting an IC50 of 34 microM, while a first cytoplasmic loop peptide weakly inhibited binding with an IC50 of approximately 1100 microM. The first and third cytoplasmic loop peptides also inhibited P-Rh* interaction with both ARR[delta (2-16)-404], an arrestin mutant that lacks residues 2-16, and ARR[1-191], a mutant that contains only the amino half of arrestin. However, the third loop peptide had an approximately 5-fold lower affinity at inhibiting the binding of ARR[1-191] to P-Rh*. While the first and third loop peptides also inhibited arrestin binding to light-activated rhodopsin and a truncated rhodopsin lacking its C-terminal sites of phosphorylation, the peptides modestly enhanced arrestin binding to phosphorylated dark rhodopsin. These results suggest that the third and, to a lesser extent, the first cytoplasmic loops of rhodopsin may play an important role in arrestin binding to light-activated forms of rhodopsin.
authors.affiliation: Department of Pharmacology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
authors.forename: J G
authors.initials: JG
authors.lastname: Krupnick
authors.forename: V V
authors.initials: VV
authors.lastname: Gurevich
authors.forename: T
authors.initials: T
authors.lastname: Schepers
authors.forename: H E
authors.initials: HE
authors.lastname: Hamm
authors.forename: J L
authors.initials: JL
authors.lastname: Benovic
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D019393:Arrestin; D001667:Binding, Competitive; D002417:Cattle; D018076:DNA, Complementary / Q000378:metabolism; D005136:Eye Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D012243:Rhodopsin / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D000941:Antigens; D019393:Arrestin; D018076:DNA, Complementary; D005136:Eye Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D010455:Peptides; D011994:Recombinant Proteins; D012243:Rhodopsin