Evidence that myosin light chain phosphorylation regulates contraction in the body wall muscles of the sea cucumber

W. G.L. Kerrick, L. L. Bolles

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The Ca2+ activation mechanism of the longitudinal body wall muscles of Parastichopus californicus (sea cucumber) was studied using skinned muscle fiber bundles. Reversible phosphorylation of the myosin light chains correlated with Ca2+-activated tension and relaxation. Pretreatment of the skinned fibers with ATPγS and high Ca2+ (10-5M) resulted in irreversible thiophosphorylation of the myosin light chains and activation of a Ca2+ insensitive tension. In contrast, pretreatment with low Ca2+ (10-8M) and ATPγS results in no thiophosphorylation of the myosin light chains or irreversible activation of tension. These results are consistent with a Ca2+-sensitive myosin light chain kinase/phosphatase system being responsible for the activation of the muscle. Other agents known to have an effect upon the Ca2+-activated tension in skinned vertebrate smooth muscle fibers (trifluoperazine, catalytic subunit of the cyclic AMP-dependent protein kinase, and calmodulin) did not have an effect on myosin light chain phosphorylation or Ca2+-activated tension. These results suggest a different type of myosin light chain kinase than is found in vertebrate smooth muscle is responsible for the activation of parastichopus longitudinal body wall muscle.

Original languageEnglish (US)
Pages (from-to)307-315
Number of pages9
JournalJournal of Cellular Physiology
Volume112
Issue number3
DOIs
StatePublished - Sep 1982

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology

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