Mitosis-specific phosphorylation of caldesmon: possible molecular mechanism of cell rounding during mitosis.
One of the profound changes in cellular morphology during mitosis is a massive alteration in the organization of microfilament cytoskeleton. It has been recently discovered that nonmuscle caldesmon, an actin and calmodulin binding microfilament-associated protein of relative molecular mass Mr = 83,000, is dissociated from microfilaments during mitosis, apparently as a consequence of mitosis-specific phosphorylation. cdc2 kinase, which is a catalytic subunit of MPF (maturation or mitosis promoting factor), is found to be responsible for the mitosis-specific phosphorylation of caldesmon. Because caldesmon is implicated in the regulation of actin myosin interactions and/or microfilament organization, these results suggest that cdc2 kinase directly affects microfilament re-organization during mitosis.
Yamashiro
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Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854-1059.
Matsumura
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D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007399:Interphase; D008938:Mitosis; D008954:Models, Biological; D010766:Phosphorylation
D002148:Calmodulin-Binding Proteins; D016203:CDC2 Protein Kinase