Myosin light chain kinase and the role of myosin light chain phosphorylation in skeletal muscle

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Skeletal muscle myosin light chain kinase (skMLCK) is a dedicated Ca 2+/calmodulin-dependent serine-threonine protein kinase that phosphorylates the regulatory light chain (RLC) of sarcomeric myosin. It is expressed from the MYLK2 gene specifically in skeletal muscle fibers with most abundance in fast contracting muscles. Biochemically, activation occurs with Ca2+ binding to calmodulin forming a (Ca2+) 4•calmodulin complex sufficient for activation with a diffusion limited, stoichiometric binding and displacement of a regulatory segment from skMLCK catalytic core. The N-terminal sequence of RLC then extends through the exposed catalytic cleft for Ser15 phosphorylation. Removal of Ca2+ results in the slow dissociation of calmodulin and inactivation of skMLCK. Combined biochemical properties provide unique features for the physiological responsiveness of RLC phosphorylation, including (1) rapid activation of MLCK by Ca2+/calmodulin, (2) limiting kinase activity so phosphorylation is slower than contraction, (3) slow MLCK inactivation after relaxation and (4) much greater kinase activity relative to myosin light chain phosphatase (MLCP). SkMLCK phosphorylation of myosin RLC modulates mechanical aspects of vertebrate skeletal muscle function. In permeabilized skeletal muscle fibers, phosphorylation-mediated alterations in myosin structure increase the rate of force-generation by myosin cross bridges to increase Ca2+-sensitivity of the contractile apparatus. Stimulation-induced increases in RLC phosphorylation in intact muscle produces isometric and concentric force potentiation to enhance dynamic aspects of muscle work and power in unfatigued or fatigued muscle. Moreover, RLC phosphorylation-mediated enhancements may interact with neural strategies for human skeletal muscle activation to ameliorate either central or peripheral aspects of fatigue.

Original languageEnglish (US)
Pages (from-to)120-128
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume510
Issue number2
DOIs
StatePublished - Jun 15 2011

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Myosin-Light-Chain Kinase
Myosin Light Chains
Phosphorylation
Muscle
Skeletal Muscle
Skeletal Muscle Myosins
Calmodulin
Myosins
Chemical activation
Light
Muscles
Skeletal Muscle Fibers
Phosphotransferases
Myosin-Light-Chain Phosphatase
Calcium-Calmodulin-Dependent Protein Kinases
Protein-Serine-Threonine Kinases
Fibers
Fatigue
Vertebrates
Catalytic Domain

Keywords

  • Calcium
  • Calmodulin
  • Contraction
  • Myosin light chain kinase
  • Regulatory light chain

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Myosin light chain kinase and the role of myosin light chain phosphorylation in skeletal muscle. / Stull, James T.; Kamm, Kristine E.; Vandenboom, Rene.

In: Archives of Biochemistry and Biophysics, Vol. 510, No. 2, 15.06.2011, p. 120-128.

Research output: Contribution to journalArticle

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