Calcium sensitivity of abalone, Haliotis discus, myosin

Superprecipitation was observed with abalone myosin and purified rabbit actin in the presence of calcium ions, but was not observed in the absence of calcium. The Mg-ATPase [EC 3.6.1.3] activity of abalone myosin and rabbit actin in the absence of calcium ions (EGTA present) showed about 60% inhibition as compared with values in the presence of calcium ions. The calcium sensitivity may be attributable to abalone myosin, as in the case of scallop myosin.