title: Calcium/calmodulin-dependent kinase II phosphorylates Drosophila visual arrestin.
abstract: Light activation of rhodopsin in the Drosophila photoreceptor induces a G protein-coupled signaling cascade that results in the influx of Ca2+ into the photoreceptor cells. Immediately following light activation, phosphorylation of a photoreceptor-specific protein, phosrestin I, is detected. Strong sequence similarity to mammalian arrestin and electroretinograms of phosrestin mutants suggest that phosrestin I is involved in light inactivation. We are interested in identifying the protein kinase responsible for the phosphorylation of phosrestin I to link the transmembrane signaling to the light-adaptive response. Type II Ca2+/calmodulin-dependent kinase is one of the major classes of protein kinases that regulate cellular responses to transmembrane signals. We show here that partially purified phosrestin I kinase activity can be immunodepleted and immunodetected with antibodies to Ca2+/calmodulin-dependent kinase II and that the kinase activity exhibits regulatory properties that are unique to Ca2+/calmodulin-dependent kinase II such as Ca2+ independence after autophosphorylation and inhibition by synthetic peptides containing the Ca2+/calmodulin-dependent kinase II autoinhibitory domain. We also show that Ca2+/calmodulin-dependent kinase KII activity is present in Drosophila eye preparations. These results are consistent with our hypothesis that Ca2+/calmodulin-dependent kinase II phosphorylates phosrestin I. We suggest that Ca2+/calmodulin-dependent kinase II plays a regulatory role in Drosophila photoreceptor light adaptation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
authors.forename: E S
authors.initials: ES
authors.lastname: Kahn
authors.forename: H
authors.initials: H
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D019390:Arrestins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D004330:Drosophila / Q000378:metabolism*; D004789:Enzyme Activation; D005123:Eye / Q000378:metabolism; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000302:isolation & purification
chemical_list: D000906:Antibodies; D019390:Arrestins; D010750:Phosphoproteins; D010770:Phosphotransferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases