Final answer:
True. Active transport proteins are often regulated by phosphorylation, which activates their transport activity.
Step-by-step explanation:
True. Active transport proteins, which are responsible for moving substances across the cell membrane against their concentration gradients, are often regulated by phosphorylation. Phosphorylation is the addition of a phosphate group to a protein, and it can activate or deactivate the protein's function. In the case of active transport proteins, phosphorylation is often a mechanism for activating their transport activity.