How Do Protein Kinases Generally Activate Their Target Proteins

Multiple Choice

How do protein kinases generally activate their target proteins?

A) The process of phosphorylation causes the target proteins to change conformation.
B) The kinases bind to target proteins directly, forming a complex that activates the proteins and lets them change conformation.
C) Kinase concentrations vary during the cell cycle, so that proteins are activated only when kinase levels are high.
D) Kinases bind to target proteins and inactivate them, so kinase levels must drop for target protein activation.
E) The process of dephosphorylation causes the target proteins to change conformation.