Phosphorylysis of Adenosine Triphosphate and Rate of Contraction of Myosin B Threads

Abstract

Phosphorylysis of ATP by myosin B is greatly accelerated in the presence of Ca. The rate is not altered in the presence of Mg. The rate of shortening of myosin B threads is inhibited by Ca and accelerated by Mg. These results suggest that phosphorylysis of ATP is not directly involved in shortening of myosin B threads.