Activation of human CDC2 protein as a histone H1 kinase is associated with complex formation with the p62 subunit

Brizuela, L., Draetta, G., Beach, D. (June 1989) Activation of human CDC2 protein as a histone H1 kinase is associated with complex formation with the p62 subunit. Proc Natl Acad Sci U S A, 86 (12). pp. 4362-6. ISSN 1091-6490

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p34 kinase, the product of the CDC2 gene, is a cell-cycle regulated protein kinase that is most active during mitosis. In HeLa cells, p34 kinase has previously been shown to exist in both a low- and a high-molecular-mass form, the latter of which is only found in cells in the G2/M phase of the cell cycle and contains a 62-kDa subunit. Here we show that although each form of the kinase phosphorylates casein in vitro, only the high-molecular-mass form uses histone H1 as substrate. The high-molecular-mass form of p34 kinase from nocodazole-treated HeLa cells was purified 6700-fold. The apparent molecular mass of the mitotic CDC2-encoded protein kinase complex was 220 kDa. The purified enzyme phosphorylated not only its endogenous 62-kDa subunit but also phosphorylated histone H1 with a Km of 3 microM and used ATP 40 times more efficiently than GTP (Km 54 microM and 2 mM, respectively). The enzyme activity was unaffected by cAMP, calcium/calmodulin, or by the heat-stable inhibitor of cAMP-dependent protein kinase. These characteristics are typical of growth-associated histone H1 kinase from different organisms. These results suggest that CDC2 protein may be activated as an M-phase-specific protein kinase in part by its association with the p62 subunit.

Item Type: Paper
Uncontrolled Keywords: CDC2 Protein Kinase Cell Cycle Chromatography, DEAE-Cellulose Chromatography, Gel Chromatography, Ion Exchange Enzyme Activation Hela Cells/cytology/enzymology Humans Kinetics Macromolecular Substances Molecular Weight Phosphoproteins/isolation & purification/*metabolism Protamine Kinase/*metabolism Protein Kinases/*metabolism Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. Substrate Specificity
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > kinase > Protein kinase C
CSHL Authors:
Communities: CSHL labs > Beach lab
Depositing User: Gail Sherman
Date: June 1989
Date Deposited: 28 Jul 2017 17:08
Last Modified: 09 Nov 2017 20:46
PMCID: PMC287269
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