Chemical modification of lysine and arginine residues in the myosin regulatory light chain inhibits phosphorylation

Abstract

The contribution of lysine and arginine residues to the substrate specificity of the myosin light-chain kinase has been studied using chemically modified myosin light chains. Succinylation of maleylation of the myosin light chains caused complete inhibition of their phosphorylation. Modification of 50% of the lysine residues resulted in 90% inhibition of phosphorylation and this was accompanied by a 25-fold increase in the apparent Km. In contrast, phosphorylation of the myosin light chains by the cAMP-dependent protein kinase was relatively insensitive to lysine modification, with only a 15% reduction in phosphorylation following succinylation of 50% of the lysine residues. Treatment with e..