Question

The role of CAK is to:

a. activate MPF by phosphorylating the kinase subunit
b. activate MPF by phosphorylating the cyclin subunit
c. inactivate MPF by phosphorylating the kinase subunit
d. inactivate MPF by phosphorylating the cyclin subunit
e. none of the above

Answer 1

CAK activates MPF by phosphorylating the kinase subunit, leading to the progression of the cell cycle. Hence, option a) is correct.

Step-by-step explanation:

CAK, or cyclin-dependent kinase activating kinase, plays a role in regulating the cell cycle. It activates MPF (maturation-promoting factor) by phosphorylating the kinase subunit. MPF is a complex of two subunits, cyclin and cyclin-dependent kinase (cdk).

The cyclin subunit levels fluctuate during the cell cycle, while the cdk subunit levels remain stable. CAK's phosphorylation of the kinase subunit of MPF leads to the activation of MPF and progression of the cell cycle.