Which of the Following is a Substrate of Cln3-Cdc28

Question

Which of the following is a substrate of Cln3-Cdc28?
A)SBF
B)SPF
C)MPF
D)MBF

Accepted Answer

Cln3-Cdc28 is a cyclin-dependent kinase complex responsible for initiating the G1 to S phase transition in the cell cycle. SBF (Swi4-Swi6) is a transcription factor that regulates genes involved in DNA replication and cell division. It is a substrate of Cln3-Cdc28 and is phosphorylated by the complex to activate the expression of genes needed for the G1 to S phase transition. SPF, MPF, and MBF are not substrates of Cln3-Cdc28. SPF stands for the Spindle Pole Body function, MPF (Maturation Promoting Factor) is a complex involved in the G2 to M phase transition, and MBF (MluI cell cycle Box Binding Factor) is a transcription factor that also regulates genes involved in DNA replication and cell division, but is regulated by other cyclin-dependent kinase complexes.