Phosphorylation of smooth muscle myosin: evidence for cooperativity between the myosin heads.

ABSTRACT

The relationship between the actin-activated adenosinetriphosphatase activity of smooth muscle myosin and the extent of myosin light chain phosphorylation is nonlinear. It is suggested that the phosphorylation of the two heads of smooth muscle myosin is an ordered process and that the two heads are influenced by cooperative interactions.