Roles and regulation of Cln-Cdc28 kinases at the start of the cell cycle of Saccharomyces cerevisiae.

摘要: In budding yeast G1 cells increase in cell mass until they reach a critical size, at which point (called Start) enter S phase, bud and duplicate their spindle pole bodies. Activation of the Cdc28 protein kinase by G1-specific cyclins Cln1, Cln2 or Cln3 is necessary for all three Start events. Transcriptional activation CLN1 CLN2 SBF MBF transcription factors also requires an active Cln-Cdc28 it has therefore been proposed that sudden accumulation transcripts during late occurs via positive feedback loop. We report whereas Cln1 are required punctual execution most, if not all, other Start-related events, SBF- MBF-driven transcription. Cln3, on hand, essential. By turning off cyclin B proteolysis B-Cdc28 inhibitor p40SIC1, kinases activate thereby trigger phase. Thus starts cycle set motion prior MBF-mediated Cln3-Cdc28 kinase. This dissection regulatory events demands rethinking as single process causes to be committed mitotic cycle.