We have cloned two different human cDNAs that can complement cdc28 mutations of budding yeast Saccharomyces cerevisiae. One corresponds to a gene encoding human p34(CDC2) kinase, and the other to a gene (CDK2; cell division kinase) that has not been characterized previously. The CDK2 protein is highly homologous to p34(CDC2) kinase (65% identical) and more significantly is homologous to Xenopus Eg1 kinase (89% identical), suggesting that CDK2 is the human homolog of Eg1. The human CDC2 and CDK2 genes were both able to complement the inviability of a null allele of S. cerevisiae CDC28. This result indicates that the CDK2 protein has a biological activity closely related to the CDC28 and p34(CDC2) kinases. However, CDK2 was unable to complement cdc2 mutants in fission yeast Schizosaccharomyces pombe under the condition where the human CDC2 gene could complement them. CDK2 mRNA appeared late in G1 or in early S phase, slightly before CDC2 mRNA, after growth stimulation in normal human fibroblast cells. These results suggest that in human cells, two different CDC2-like kinases may regulate the cell cycle at distinct stages.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - Jan 1 1991|
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