Calmodulin, a heat stable Ca^(++)-binding protein, is a multifunctional modulator, mediating many of the Ca^(++) effects in cellular functions. This protein interacts reversibly with Ca^(++) to form a protein/ Ca^(++) complex, whose activity is regula...
Calmodulin, a heat stable Ca^(++)-binding protein, is a multifunctional modulator, mediating many of the Ca^(++) effects in cellular functions. This protein interacts reversibly with Ca^(++) to form a protein/ Ca^(++) complex, whose activity is regulated by cellular flux of Ca^(++). Calmodulin from bovine brain was purified to complete homogeneity by heat, acid treatment and hydrophobic interaction chromatography. The biochemical properties of the purified protein were examined under various criteria. It was estimated to have an apparent molecular weight of 21K and 15K in the absence or presence of Ca^(++) respectively, which would mean the great conformational changes were induced by the binding of Ca^(++) to calmodulin. The calmodulin had distinct ultraviolet absorption peaks at 259, 265, and 279 nm due to phenylalanine and tyrosine residues. Also, this protein activated the Ins(1,4,5) P₃-Kinase of which role is very important in cellular signal transduction, about seven folds (at 6 μM Ca^(++) and 1.0 μM calmodulin) with a Ca^(++)-dependent manner.