Exchange of 20-kDa myosin light chain-bound phosphate during sustained contraction of arterial smooth muscle.

Abstract

K(+)-contracted porcine carotid arterial muscles containing phosphorylated 20-kDa myosin light chains (LC) were exposed to carrier-free [32P]orthophosphate in K(+)-stimulating solution during sustained contraction. The covalently bound LC phosphate was completely replaced by [32P]phosphate, indicating that myosin light chain phosphatase and kinase have ready access to the bound phosphate during the sustained contraction. On average, 0.38 mol [32P]phosphate was incorporated per mole LC during the sustained K+ contraction. This value was about half of the maximal value for [32P]phosphate incorporation into LC, 0.74 mol/mol, in muscles contracted with K+ for 1 min. Assuming that sustained contraction involves the maximal number of cross-bridges attached to actin, the data suggest that half of the attached cross-bridges contain phosphorylated LC.

Cite this paper

@article{Brny1991ExchangeO2, title={Exchange of 20-kDa myosin light chain-bound phosphate during sustained contraction of arterial smooth muscle.}, author={Michael B{\'a}r{\'a}ny and Aniko Rokolya and Kate B{\'a}r{\'a}ny}, journal={Archives of biochemistry and biophysics}, year={1991}, volume={287 1}, pages={199-203} }