[Effect of fatty acids on calmodulin regulation of adenylate cyclase from the brain striatal system]

p3eincubation of striatal membranes for 1 hour at 37 degrees C in the presence of calmodulin results in thermal inactivation of the calmodulin-insensitive adenylate cyclase; the activity of the calmodulin-sensitive form of the enzyme remains practically unchanged. Using a membrane preparation of striatal adenylate cyclase possessing a high sensitivity to calmodulin, the effects of fatty acids on regulation of adenylate cyclase by Ca2+ and calmodulin were studied. It was found that linolenic and palmitic acids exert a weak activating effect on adenylate cyclase in the presence of Ca2+, but do not practically affect the enzyme in Ca2+ free media. Linolenic acid almost completely inhibits the activation of adenylate cyclase by calmodulin; palmitic acid has no such effect. It was assumed that unsaturated fatty acids may prevent the interaction of adenylate cyclase with calmodulin.