Phosphorylation of smooth muscle myosin by type II Ca2+/calmodulin-dependent protein kinase |
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Authors: | Arthur M Edelman Wei-Hsung Lin Donna J Osterhout Mark K Bennett Mary B Kennedy Edwin G Krebs |
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Institution: | (1) Department of Pharmacology and Therapeutics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 14214 Buffalo, New York, USA;(2) Division of Biology, 216-76, California Institute of Technology, 91125 Pasadena, California, USA;(3) Howard Hughes Medical Institute, University of Washington, 98195 Seattle, WA, USA |
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Abstract: | Brain type II Ca2+/calmodulin-dependent protein kinase was found to phoshorylate smooth muscle myosin, incorporating maximally 2 mol of phosphoryl per mol of myosin, exclusively on the 20,000 dalton light chain subunit. After maximal phosphorylation of myosin or the isolated 20,000 dalton light chain subunit by myosin light chain kinase, the addition of type II Ca2+/calmodulin-dependent protein kinase led to no further incorporation indicating the two kinases phosphorylated a common site. This conclusion was supported by two dimensional mapping of tryptic digests of myosin phosphorylated by the two kinases. By phosphoamino acid analysis the phosphorylated residue was identified as a serine. The phosphorylation by type II Ca 2+/calmodulin-dependent protein kinase of myosin resulted in enhancement of its actin-activated Mg2+-ATPase activity. Taken together, these data strongly support the conclusion that type II Ca2+/calmodulin-dependent protein kinase phosphorylates the same amino acid residue on the 20,000 dalton light chain subunit of smooth muscle myosin as is phosphorylated by myosin light chain kinase and suggest an alternative mechanism for the regulation of actin-myosin interaction.Abbreviations SDS-PAGE
Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis
- EGTA
Ethylene Glycol Bis (-amino-ethyl ether)-N,N,N,N-Tetraacetic Acid
- DTT
Dithiothreitol
- LC20
Gizzard Smooth Muscle Phosphorylatable 20 kDa Myosin Light Chain
- LC17
Gizzard Smooth Muscle, 17 kDa Myosin Light Chain
- H Chain
Gizzard Smooth Muscle 200 kDa Myosin Heavy Chain
- TPCK
L-1-Tosylamido-2-Phenylethyl Chloromethyl Ketone
- MOPS
3-(N-morpholino) Propanesulfonic Acid |
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Keywords: | myosin calcium calmodulin type II kinase |
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