title: Calmodulin activation of cyclic AMP phosphodiesterase in the B16 mouse melanoma.
abstract: Mouse B16 melanoma extracts of both cultured cells and tumour tissue contain cyclic AMP phosphodiesterase activity, with 95% present in the soluble fraction. Although activation of the enzyme by added calmodulin did not occur, it was found that endogenous calmodulin was present at a level sufficient to activate fully the enzyme. The ability of Ca-calmodulin to stimulate cyclic AMP phosphodiesterase in this tissue was shown by the inhibitory effect of N-(6-aminohexyl)-5-chloronaphthalenesulphonamide (W7), a known calmodulin antagonist; by the activation of the enzyme with exogenous calmodulin observed in supernatants depleted of endogenous calmodulin by passage over fluphenazine-Sepharose 6B in the presence of Ca2+; by the Ca-dependent binding of the enzyme to calmodulin-agarose and its activation by Ca-calmodulin after elution from the column with EGTA-containing buffer. It was calculated that about 50% of the total cyclic AMP phosphodiesterase activity was calmodulin-activated in this tissue.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D008545:Melanoma / Q000201:enzymology*; D051379:Mice; D012685:Sepharose; D013347:Subcellular Fractions / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D012685:Sepharose; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases