Modulation of smooth muscle calponin by protein kinase C and calmodulin.
When smooth muscle calponin was incubated with protein kinase C, 1 mole of phosphate was incorporated per mole of calponin. The apparent Km value for calponin of the protein kinase was about 0.4 microM. The phosphorylation of calponin by protein kinase C was inhibited markedly by calmodulin in a calcium-dependent manner. Kinetic analysis of calmodulin-induced inhibition of calponin phosphorylation by protein kinase C revealed that calmodulin inhibited the phosphorylation in a noncompetitive fashion with calponin and the determined Ki value was 0.4 microM. These results suggest that interaction of calmodulin with calponin may play a regulatory role in the phosphorylation by protein kinase C and smooth muscle contraction.
Naka
M
M
Department of Molecular and Cellular Pharmacology, Mie University School of Medicine, Japan.
Kureishi
Y
Y
Muroga
Y
Y
Takahashi
K
K
Ito
M
M
Tanaka
T
T
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism* / Q000494:pharmacology; D002645:Chickens; D005895:Gizzard, Avian / Q000378:metabolism; D007700:Kinetics; D008840:Microfilament Proteins; D009124:Muscle Proteins / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D000096985:Calponins
D002118:Calcium; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D008840:Microfilament Proteins; D009124:Muscle Proteins; D011493:Protein Kinase C; D000096985:Calponins