A cdc2-related kinase oscillates in the cell cycle independently of cyclins G2/M and cdc2.
The Eg1 gene in Xenopus laevis is related in sequence to the cdc2+ gene. We show here that the Eg1 gene product (cdk2) possesses histone H1 protein kinase activity and binds to PSTAIR antibodies as well as to Sepharose beads linked to the 13-kDa product of the suc 1 gene (p13suc1). Eg1 protein kinase is active only in an Mr approximately 200,000 complex with other proteins but is not associated with any of the three known Xenopus mitotic cyclins or with any newly synthesized protein in egg extracts that exhibit cell cycle oscillations in vitro. The protein kinase activity of Eg1 oscillates in the mitotic cell cycle, being high in M-phase and low in interphase. Hyperactivation of cdc2 kinase by the addition of cyclin A has no effect on the activity or oscillatory behavior of Eg1. Inhibition of cdc2 kinase activation by emetine or RNase treatment of oscillating extracts does not inhibit the activation of Eg1 but does block deactivation normally seen during exit from mitosis. These results indicate that Eg1 is regulated by a cell cycle clock independently of cyclin and cdc2 kinase.
Gabrielli
B G
BG
Howard Hughes Medical Institute, University of Colorado School of Medicine, Denver 80262.
Roy
L M
LM
Gautier
J
J
Philippe
M
M
Maller
J L
JL
D000595:Amino Acid Sequence; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000502:physiology; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D007106:Immune Sera; D007118:Immunoassay; D007700:Kinetics; D008938:Mitosis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D010766:Phosphorylation; D006656:Protamine Kinase / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D013379:Substrate Specificity; D029867:Xenopus Proteins; D014982:Xenopus laevis
D007106:Immune Sera; D010455:Peptides; D029867:Xenopus Proteins; D011494:Protein Kinases; D006656:Protamine Kinase; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495891:Cdk2 protein, Xenopus; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases