#Question id: 2974

Following statements are regarding to control of the G1–S phase transition in budding yeast.

A. G1 cyclin-CDK complexes stimulate the formation of G1/S phase cyclin-CDKs, which then initiate bud formation, centrosome duplication, and DNA replication. In yeast, the G1 cyclin gene is called CLN3.

B. Once sufficient Cln3 is synthesized from its mRNA, Cln3-CDK complexes phosphorylate and activate the transcriptional repressor Whi5.

C. Phosphorylation of Whi5 promotes its export out of the nucleus, allowing the transcription factor complex SBF to induce transcription of the G1/S phase cyclin genes CLN1 and CLN2 as well as other genes important for DNA replication.

D. Once produced, Cln1/2-CDKs contribute to further Whi5 phosphorylation. This positive feedback loop ensures the rapid accumulation of G1/S phase cyclin-CDKs.

Which of the following statements are correct?