Final answer:
Phospholipase C activates two signaling pathways by cleaving PIP2 into DAG and IP3. DAG activates protein kinase C, while IP3 releases Ca2+ ions from the endoplasmic reticulum, both of which lead to further signal transduction within the cell.
Step-by-step explanation:
Phospholipase C and Signaling Pathways
Phospholipase C (PLC) is an enzyme that activates two distinct signaling pathways upon cleavage of a particular phospholipid, PIP2. Once a ligand binds to a cell's receptor and activates PLC, PIP2 is split to form diacylglycerol (DAG) and inositol triphosphate (IP3), both serving as second messengers. The DAG remains in the plasma membrane and acts to activate protein kinase C (PKC), which then phosphorylates serine and threonine residues on target proteins. Simultaneously, IP3 diffuses into the cytoplasm, where it triggers ligand-gated calcium channels in the endoplasmic reticulum to release Ca2+. The released Ca2+ ions further propagate the signaling cascade, which can lead to various cellular responses such as muscle contraction, secretion, metabolism regulation, or even cell death through apoptosis.