Inhibition by calmodulin of calcium/phospholipid-dependent protein phosphorylation.
Calmodulin was previously found to inhibit the Ca2+/phospholipid-dependent phosphorylation of an endogenous substrate, called the 87-kilodalton protein, in a crude extract prepared from rat brain synaptosomal cytosol. We investigated the mechanism of this inhibition, using Ca2+/phospholipid-dependent protein kinase and the 87-kilodalton protein, both of which had been purified to homogeneity from bovine brain. Rabbit brain calmodulin and some other Ca2+-binding proteins inhibited the phosphorylation of the 87-kilodalton protein by this kinase in the purified system. Calmodulin also inhibited the Ca2+/phospholipid-dependent phosphorylation of H1 histone, synapsin I, and the delta subunit of the acetylcholine receptor, with use of purified components. These results suggest that calmodulin may be a physiological regulator of Ca2+/phospholipid-dependent protein kinase.
D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000502:physiology; D002147:Calmodulin / Q000494:pharmacology*; D002417:Cattle; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D011493:Protein Kinase C; D002118:Calcium