Question

Dynamic phosphorylation/dephosphorylation is key to proper cell cycle control in that: (select all answers that apply)

	A.	CAKs phosphorylate (and activate) CDK subunits.
	B.	Wee1 kinase phosphorylates (and activates) CDK subunits.
	C.	Cdc25 kinase phosphorylates (and activates) CDK subunits.
	D.	Phosphorylation of the CKI Sic1 directs its subsequent ubiquitination and proteasomal degradation.
	E.	Kinases phosphorylate (and activate) SCF, the ubiquitin ligase responsible for degradation of G1/S phase cyclins.

Answer 1

The correct answers are:

Kinases phosphorylate (and activate) SCF, the ubiquitin ligase responsible for degradation of G1/S phase cyclins.

CAKs phosphorylate (and activate) CDK subunits..

Mostly the cyclin CDK complexes regulate the cell cycle. Animals containing CDK 1, 2, 3 are directly involved in the regulation of cell cycle. These complexes phosphorylate substrates that are involved in cell cycle. The CAK 1 is a monomeric protein complex consisting of Cak1. It phosphorylates the Cdk and is responsible for its activation. The Skp-1 or SCf type E3 ubiquitin ligase complex is responsible for regulating the cellular level of ubiquitylation and proteolysis. SCF complexes are implicated in G1 - S progression, and anaphase promoting complex which are required for the separation of sister chromatids at anaphase and exit from Mphase into G1.