Some g protein-coupled receptors are sensitve to hormones such as angiotensin ii and oxytocin, and act through compounds such as phospholipase c and ip3. (a) complete the flowchart showing the cleavage of a membrane lipid to form compounds that ultimately cause the phosphorylation of specific proteins. the abbreviations used are phosphatidylinositol 4,5-bisphosphate, pip2; protein kinase c, pkc; diacylglycerol, dag; and inositol 1 ,4,5-triphosphate, ip3; phospholipase c, plc. b)which of the compounds can be considered second messengers? 1-dag 2-pkc 3-ser 4-ip3 5-pip2 6-plc 7-ca2+ !