Nucleotide regulatory sites on skeletal myosin

Abstract

Myosin Ca2+-ATPase activity decreased in the presence of ADP.Free ATP acted either as an activator or as an inhibitor depending on its concentration.The inhibition caused by ADP or ATP followed a competitive pattern with respect to the substrate.ATP, at activating concentrations, competed with dinitrophenol and with the anions SCN-, CN- and HCO3- for the same binding sites of myosin, whereas ADP did not compete with them.These results suggest that the nucleotide regulatory site or sites, different from the hydrolytic sites, seem to coincide with the anion binding sites.