Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catalyze removal of phosphate(s)from phosphorylated proteins. Phosphorylation and dephosphorylation can function as an on-off switch for a protein's activity, most likely through
A) the change in a protein's charge leading to a conformational change.
B) the change in a protein's charge leading to cleavage.
C) a change in the optimal pH at which a reaction will occur.
D) a change in the optimal temperature at which a reaction will occur.
E) the excision of one or more peptides.

Question

Quizplus · Accepted Answer

Phosphorylation and dephosphorylation can cause a change in a protein's charge, which can lead to a conformational change and a switch in its activity. This is the most common mechanism by which protein kinases and phosphatases regulate protein activity.

Protein Kinases Are Enzymes That Catalyze Phosphorylation of Target Proteins