Porcine left ventricular cardiac myosin and rabbit white skeletal myosin were phosphorylated by rabbit skeletal myosin light chain kinase and their Ca2+ binding properties were examined by equilibrium dialysis techniques. No significant effect of phosphorylation on the Ca2+ binding properties of these myosins was observed. Both types of striated muscle myosins bound approximately 2 mol of Ca2+/mol of myosin with similar affinities of 3 x 107 M-1. In the presence of 3 x 10-4 M Mg2+ the myosins bound Ca2+ with a reduced affinity of 3 to 4 x 105 M-1. Assuming competition between Mg2+ and Ca2+ for the binding sites on myosin, the changes in Ca2+ binding can be accounted for by a Mg2+ affinity of 2.5 to 3.0 x 105 M-1.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Biological Chemistry|
|State||Published - 1979|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology