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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7272

Marivonne Rodriguez, Jeong W. Cho, Helmut W. Sauer, and Peter J. Rizzo; Evidence for the Presence of a cdc2-like Protein Kinase in the Dinoflagellate Crypthecodinium cohnii. J.Eukaryot.Microbiol. 40(1):91-96, 1993

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The unusual nature of mitosis and ancestral organization of the dinoflagellate nucleus prompted the question of whether the cdc2-like histone H1 kinase, a presumed ubiquitous cell cycle regulator in eukaryotes, is present in these primitive organisms. Western blotting of Crypthecodinium cohnii protein extracts using antibody against the Pro-Ser-Thr-Ala-Ile-Arg-Glu (=PSTAIRE) amino acid sequence motif, conserved in all cdc2 homologues known, revealed one prominent band corresponding to a protein with an apparent relative molecular weight ~~34,000, identical in mobility to that from HeLa cells and Physarum polycephalum, higher and lower eukaryotic controls, respectively. Incubation of C. cohnii cell lysates with p13(suc1)-sepharose beads, which preferentially, though not exclusively, bind p34(cdc2), resulted in precipitation of a 34-kDa protein which was reactive with anti-PSTAIRE antibody, selectively competed for by the PSTAIRE peptide and able to phosphorylate histone H1 in vitro. We conclude that the dinoflagellate C. cohnii contains a protein very similar to the cdc2 gene product from fission yeast and its homologues in all eukaryotes studied thus far.