G1-specific cyclins: in search of an S-phase-promoting factor.
In budding yeast, Saccharomyces cerevisiae, the two principal cell cycle transitions, from G1 to S phase and from G2 to M phase, are controlled by the same protein from G2 to M phase, are controlled by the same protein kinase, CDC28, a homolog of the cdc2 protein kinase in fission yeast and other organisms. The G1 to S phase activity of the kinase is associated with accumulation of a novel family of G1 cyclins, distinct from cyclins that are required to activate the kinase for G2 to M phase functions. It remains to be determined whether G1 cyclins with similar functions exist in higher cells.
Reed
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Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.
D000595:Amino Acid Sequence; D000818:Animals; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle; D016213:Cyclins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D011494:Protein Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development*
D016213:Cyclins; D011494:Protein Kinases; D042846:CDC2-CDC28 Kinases