Title: 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.
Publication Year: 1991
Publication Date: 1991-05-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 6
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