title: Selective effects of CAPP1-calmodulin on its target proteins.
abstract: Occupancy of one of the two phenothiazine-binding sites on calmodulin does not significantly decrease the affinity of calmodulin for its target proteins; however, it does affect the ability of calmodulin to activate some enzymes. Previously we demonstrated that a covalent adduct of calmodulin with one molecule of phenothiazine (CAPP1-calmodulin) is an antagonist for the calmodulin-dependent enzymes, cAMP phosphodiesterase and myosin kinase, and a partial agonist for calcineurin. We now show that CAPP1-calmodulin is a full agonist for glycogen synthase kinase and phosphorylase kinase. Unlike phenothiazines, CAPP1-calmodulin is specific for calmodulin-regulated proteins; it has no effect on protein kinase C. With the exception of phosphorylase kinase, occupancy of two phenothiazine-binding sites completely eliminates the ability of calmodulin to activate these proteins. Thus, the study of the interaction of CAPP1-calmodulin with calmodulin target proteins demonstrates that calmodulin interacts differently with different proteins. This is confirmed by studies of the effect of calmodulin fragments, 1-77 and 78-148, on calmodulin-regulated enzymes.
authors.forename: D
authors.initials: D
authors.lastname: Newton
authors.forename: C
authors.initials: C
authors.lastname: Klee
authors.forename: J
authors.initials: J
authors.lastname: Woodgett
authors.forename: P
authors.initials: P
authors.lastname: Cohen
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002147:Calmodulin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D038341:Glycogen Synthase Kinases; D066298:In Vitro Techniques; D010640:Phenothiazines / Q000378:metabolism / Q000494:pharmacology*; D010764:Phosphorylase Kinase / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D010640:Phenothiazines; D011506:Proteins; C046036:phenothiazine-calmodulin complex; D011494:Protein Kinases; D010764:Phosphorylase Kinase; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C031637:phenothiazine; D002118:Calcium