p25rum1 orders S phase and mitosis by acting as an inhibitor of the p34cdc2 mitotic kinase.
p25rum1 from the fission yeast S. pombe is shown to act as a specific in vitro inhibitor of the p34cdc2/p56cdc13 mitotic kinase. It is also shown that early G1 cells contain p25rum1, which associates with and inhibits the mitotic kinase, and maintains p56cdc13 mitotic B cyclin at a low level, ensuring that these cells do not undergo a premature lethal entry into mitosis. A high level of p25rum1 in G2 cells inhibits the p34cdc2/p56cdc13 kinase that removes the block preventing a further S phase and leads to repeated rounds of DNA replication. Thus, the cyclin-dependent kinase inhibitor p25rum1, acting on the p34cdc2 mitotic kinase, plays an important role in ensuring the correct sequence of S phase and mitosis during the cell cycle.
Imperial Cancer Research Fund, London, England.
J
J
Correa-Bordes
P
P
Nurse
D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors*; D019926:Cyclin B; D016213:Cyclins / Q000037:antagonists & inhibitors / Q000378:metabolism; D004261:DNA Replication / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005656:Fungal Proteins / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D016193:G1 Phase / Q000502:physiology; D018816:Genes, cdc / Q000502:physiology; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D016196:S Phase / Q000502:physiology*; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology; D029702:Schizosaccharomyces pombe Proteins; D013696:Temperature
D019926:Cyclin B; D016213:Cyclins; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; C086077:Rum1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D016203:CDC2 Protein Kinase