Key result
Phosphorylation of porcine cardiac and rabbit skeletal myosins had no significant effect on their calcium binding properties, with both binding approximately 2 mol of Ca2+/mol of myosin.
Phosphorylation of cardiac and skeletal myosins does not significantly alter their calcium binding properties.
No effect on animal myosin Ca2+ binding cautions against assuming regulatory role clinically; leaves open relevance to human contractility.
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 10(7) 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 10(5) 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 10(5) M-1.
No takes yet. Share an insight, caveat, or question.
Holroyde et al. (1979) studied this question. Phosphorylation vs. Unphosphorylated myosin was evaluated on Ca2+ binding properties. Phosphorylation of porcine cardiac and rabbit skeletal myosins had no significant effect on their calcium binding properties, with both binding approximately 2 mol of Ca2+/mol of myosin.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: