Rhodopsin kinase inhibition by recoverin. Function of recoverin myristoylation.
Recoverin is a Ca(2+)-binding protein that may play a role in vertebrate photoreceptor light adaptation by imparting Ca2+ sensitivity to rhodopsin kinase. It is heterogeneously acylated (mostly myristoylated) at its amino-terminal glycine. Recent studies have shown that recoverin myristolyation is necessary for its Ca(2+)-dependent membrane association and cooperative Ca2+ binding. We have addressed several issues concerning the role of recoverin myristoylation with respect to inhibition of rhodopsin kinase. We find that 1) myristoylation of recoverin is not necessary for inhibition of rhodopsin kinase, 2) myristoylation of recoverin induces a cooperative Ca(2+)-dependence for rhodopsin kinase inhibition, and 3) each Ca(2+)-binding site on the nonmyristoylated recoverin partially inhibits rhodopsin kinase. The available data suggest that the functions of recoverin myristoylation in the living rod are to induce a sharp Ca2+ dependence of rhodopsin kinase inhibition and to bring this dependence into the rod's physiological Ca2+ concentration range.
Calvert
P D
PD
R. M. Bock Laboratories, University of Wisconsin, Madison 53706, USA.
Klenchin
V A
VA
Bownds
M D
MD
D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism* / Q000494:pharmacology*; D002417:Cattle; D005136:Eye Proteins; D051606:G-Protein-Coupled Receptor Kinase 1; D051597:Hippocalcin; D007700:Kinetics; D008074:Lipoproteins; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D051603:Recoverin; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D014714:Vertebrates
D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D008074:Lipoproteins; D009227:Myristic Acids; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; D019814:Myristic Acid; D051603:Recoverin; D051597:Hippocalcin; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1