Polo-like kinase is a cell cycle-regulated kinase activated during mitosis

R. Hamanaka, M. R. Smith, P. M. O'Connor, S. Maloid, K. Mihalic, J. L. Spivak, D. L. Longo, D. K. Ferris

Research output: Contribution to journalArticlepeer-review

154 Scopus citations


Previously, we demonstrated that expression of polo-like kinase (PLK) is required for cellular DNA synthesis and that overexpression of PLK is sufficient to induce DNA synthesis. We now report that the endogenous levels of PLK, its phosphorylation status, and protein kinase activity are tightly regulated during cell cycle progression. PLK protein is low in G1, accumulates during S and G2M, and is rapidly reduced after mitosis. During mitosis, PLK is phosphorylated on serine, and its serine threonine kinase function is activated at a time close to that of p34(cdc2). The phosphorylated form of PLK migrates with reduced mobility on SDS- polyacrylamide gel electrophoresis, and dephosphorylation by purified protein phosphatase 2A converts it to the more rapidly migrating form and reduces the total amount of PLK kinase activity. Purified p34(cdc2)-cyclin B complex can phosphorylate PLK protein in vitro but causes little increase in PLK kinase activity.

Original languageEnglish (US)
Pages (from-to)21086-21091
Number of pages6
JournalJournal of Biological Chemistry
Issue number36
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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