Properties of the non-specific calcium-binding sites of rabbit skeletal-muscle myosin.

The non-specific Ca2+-binding sites of skeletal-muscle myosin are located on the light chains; with the dissociation of light chains there is a corresponding decrease in the number of Ca2+-binding sites on light-chain-deficient myosin. The released light chains have a decreased binding affinity. Myosin heavy chains indirectly influence the Ca2+-binding properties of light chains by increasing the affinity of light chains for bivalent cations; this influence varies with pH. Because of light-chain dissociation at low Ca2+ and/or Mg2+ concentrations, anomalies may exist when analyses of non-specific Ca2+-binding properties of myosin are assessed by dialysis equilibrium.