Calcium-calmodulin-dependent phosphorylations in the control of muscular contraction?
Muscular contraction is triggered by the increase in free calcium concentration and modulated by cyclic nucleotide-dependent phosphorylation. Beside a direct trigger of sarcomeric muscle contraction through binding of troponin C, calcium ions trigger or modulate contractility through calcium-calmodulin-dependent myosin light chain kinases, and increase the rate of relaxation through the calmodulin-dependent phosphorylation of phospholamban, the activator of the cardiac sarcoplasmic reticulum calcium pump. In both cases, a concerted regulation by calcium and cyclic nucleotides is observed. Hyperactivation of the calcium pump is brought about by additional phosphorylation of phospholamban by cAMP-dependent protein kinase. Similarly myofibrillar myosin light chain kinases from smooth and skeletal muscles are substrates of the cAMP-dependent protein kinase. The calmodulin-dependent protein kinases are probably organized into supramolecular regulatory complexes.
D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D009200:Myocardial Contraction; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D011494:Protein Kinases; D009218:Myosins; D002118:Calcium