Modulator protein as a Ca2+-dependent activator of rabbit skeletal myosin light-chain kinase. Purification and characterization.
The Ca2+-dependent activator protein of myosin light-chain kinase, which was identified as the bovine brain modulator protein of cyclic nucleotide phosphodiesterase, was isolated from rabbit skeletal muscle. The purified protein binds about 2 Ca2+ per mol in a medium containing 5 mM MgCl2, 10 micron CaCl2, and 0.1 M KCl at pH 6.8. The Ca2+ binding caused a conformational change of the activator protein which was measured by difference ultraviolet absorption spectroscopy. In the same Ca2+ concentration range as that causing the conformational change, activation of myosin light-chain kinase was observed.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D009124:Muscle Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology*; D009218:Myosins; D010446:Peptide Fragments; D011485:Protein Binding; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits
D000596:Amino Acids; D002147:Calmodulin; D002352:Carrier Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D011494:Protein Kinases; D009218:Myosins; D008274:Magnesium; D002118:Calcium