Question

Indicate whether each of the following phosphorylation events typically activates (A) or inactivates (I) the protein that is being phosphorylated. The correct answer will be a four-letter string composed of letters A and I only, e.g. IIIA. ( ) Phosphorylation of Cdc25 by M-Cdk ( ) Phosphorylation of condensin subunits by M-Cdk ( ) Phosphorylation of APC/C by M-Cdk ( ) Phosphorylation of Ndc80 subunits by Aurora-B

Answer 1

Phosphorylation and dephosphorylation plays an important role in activating or inhibiting different proteins.

Step-by-step explanation:

1. When Cdc25 is phosphorylated by M-Cdk, it activates the CdC25. It acts as checkpoint from G1 to S and G2 to M.

So, the correct answer is activates (A).

2. Phosphorylation of condensins by M-Cdk, degrades the condensin and begins the decondensation of chromosomes. That means it inactivates the condensin.

So, the correct answer is Inactivates (I).

3. Phosphorylation of APC/C activates it and then CdC20 can bind to it and then cell will progress through anaphase.

So, the correct answer is Activation (A).

4. Phosphorylation of Ndc80 by Aurora-B leads to binding of NdC80 to kinetochore and recruits the Ska complex at kinetochore.

So the correct answer is activates (A).

So, four-letter string is AIAA.