Final answer:
Diacylglycerol (DAG) recruits and activates protein kinase C (PKC), which phosphorylates target proteins to modulate cellular functions.
Step-by-step explanation:
The enzyme that diacylglycerol (DAG) recruits and activates is protein kinase C (PKC). DAG is a lipid-derived second messenger produced by the cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) by the enzyme phospholipase C. The role of DAG in the cell is to bind to and activate PKC, which then phosphorylates serine and threonine residues on various target proteins. This phosphorylation results in changes in the activity of the target proteins, thereby modulating cellular functions. Protein kinase C activation plays a crucial role in the signal transduction pathways that lead to various cell-specific responses.