Protein kinase C mediates phosphorylation of the regulatory light chain of myosin-II during mitosis

O. Varlamova, A. Spektor, Anne R. Bresnick

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Phosphorylation of the regulatory light chain (RLC) of myosin-II is cell cycle dependent. Early in mitosis the RLC is phosphorylated predominantly on Ser-1/2, while during cytokinesis the primary site of phosphorylation is Ser-19 (Yamakita et al., 1994). To identify candidate kinases likely to mediate the mitotic phosphorylation on Ser-1/2, we assayed RLC kinase activity in mitotic cell extracts and measured apparent steady-state kinetic constants using purified enzymes. The mitotic RLC kinase is distinct from cdc2 kinase, protein kinase A and protein kinase G, as activators or inhibitors specific for these kinases do not affect the mitotic kinase activity. The activity of the mitotic RLC kinase is enhanced by the addition of Ca2+ and DAG and/or phorbol esters, characteristics of a conventional protein kinase C (PKC). Moreover, the PKC inhibitors, Gö6983 and Gö6976, significantly attenuate the phosphorylation of the RLC in mitotic extracts. Apparent steady-state kinetic studies indicate that several PKC isoforms display high specificity for myosin-II. These results suggest that current models describing Ser-1/2 phosphorylation during mitosis need to be re-evaluated.

Original languageEnglish (US)
Pages (from-to)243-250
Number of pages8
JournalJournal of Muscle Research and Cell Motility
Volume22
Issue number3
DOIs
StatePublished - 2001

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Myosin Type II
Phosphorylation
Mitosis
Protein Kinase C
Phosphotransferases
Light
Cyclic GMP-Dependent Protein Kinases
CDC2 Protein Kinase
Kinetics
Phorbol Esters
Cyclic AMP-Dependent Protein Kinases
Cytokinesis
Protein C Inhibitor
Protein Kinase Inhibitors
Cell Extracts
Protein Isoforms
Cells
Cell Cycle
Enzymes

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Endocrinology
  • Cell Biology

Cite this

Protein kinase C mediates phosphorylation of the regulatory light chain of myosin-II during mitosis. / Varlamova, O.; Spektor, A.; Bresnick, Anne R.

In: Journal of Muscle Research and Cell Motility, Vol. 22, No. 3, 2001, p. 243-250.

Research output: Contribution to journalArticle

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AB - Phosphorylation of the regulatory light chain (RLC) of myosin-II is cell cycle dependent. Early in mitosis the RLC is phosphorylated predominantly on Ser-1/2, while during cytokinesis the primary site of phosphorylation is Ser-19 (Yamakita et al., 1994). To identify candidate kinases likely to mediate the mitotic phosphorylation on Ser-1/2, we assayed RLC kinase activity in mitotic cell extracts and measured apparent steady-state kinetic constants using purified enzymes. The mitotic RLC kinase is distinct from cdc2 kinase, protein kinase A and protein kinase G, as activators or inhibitors specific for these kinases do not affect the mitotic kinase activity. The activity of the mitotic RLC kinase is enhanced by the addition of Ca2+ and DAG and/or phorbol esters, characteristics of a conventional protein kinase C (PKC). Moreover, the PKC inhibitors, Gö6983 and Gö6976, significantly attenuate the phosphorylation of the RLC in mitotic extracts. Apparent steady-state kinetic studies indicate that several PKC isoforms display high specificity for myosin-II. These results suggest that current models describing Ser-1/2 phosphorylation during mitosis need to be re-evaluated.

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