Structure of the actin–myosin interface

Abstract

The topography of the rigor complex between F-actin and myosin heads (S1) was investigated by carbodiimide zero-length cross-linking. The results demonstrate for the 1st time that the 95,000 MW (95K kilodalton) H chain of the myosin head enters into van der Waals contact with 2 neighboring actin monomers; 1 is bound to the 50K domain and the other to the 20K domain of the myosin chain. The covalent F-actin-S1 complex can be isolated; it shows a vastly elevated Mg2+-ATPase. Each pair of actin subunits in the thin filament seems to act as a functional unit for specific binding of a myosin head and stimulation of its Mg2+-ATPase activity.