Membrane phospholipids such as phosphatidylinositol 4,5-bisphosphate or PIP2, present on the cytosolic side of the membrane, function as precursors of important second messengers. Ligand-bound GPCR recruits and stimulates Gq proteins. G-α-q subunit detaches from the receptor and activates a membrane-bound enzyme, phospholipase C-ꞵ or PLC-ꞵ. PLC-ꞵ hydrolyzes PIP2 to yield two second messengers, a membrane-bound 1,2-diacylglycerol or DAG, and diffusible inositol 1,4,5-trisphosphate or IP3. IP3 binds and opens IP3-gated calcium channels on the endoplasmic reticulum membrane, releasing calcium ions in the cytosol. Increasing cytosolic calcium allows protein kinase C or PKC to translocate to the plasma membrane. It is activated by the membrane-bound DAG to phosphorylate different target proteins.