Substrate specificity of myosin light chain kinases

B. Paul Herring, Patricia J. Gallagher, James T. Stull

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Skeletal muscle myosin light chain kinase can phosphorylate myosin light chains isolated from skeletal or smooth muscle. In contrast, smooth muscle myosin light chain kinase specifically phosphorylates light chains isolated from smooth muscle. In this study, we have identified residues within the rabbit smooth and skeletal muscle myosin light chain kinases which may interact with the basic residues that are important substrate determinants in the light chains. Mutation of aspartic acid 270 ammo-terminal of the catalytic core of the skeletal muscle myosin light chain kinase increased the Km value for both smooth and skeletal muscle light chains. Although deletions of the analogous region of the smooth muscle myosin light chain kinase (residues 663-678) markedly increased the Km value for light chain, mutation of any single acidic residue within this region did not have a similar effect. Mutation of single residues within the catalytic core of the skeletal muscle (E377 and E421) and smooth muscle (E777 and E821) myosin light chain kinases increased Km values for the smooth muscle light chain at least 35- and 100-fold, respectively. It is proposed that these residues may form ionic interactions with the arginine that is 3 residues amino-terminal of the phosphorylatable serine in the smooth muscle light chain.

Original languageEnglish (US)
Pages (from-to)25945-25950
Number of pages6
JournalJournal of Biological Chemistry
Volume267
Issue number36
StatePublished - Dec 25 1992

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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