Final answer:
Phospholipase C cleaves PIP₂ to produce diacylglycerol (DAG) and inositol triphosphate (IP3), which serve as important second messengers in cellular signaling pathways, activating protein kinase C and releasing calcium ions. The correct answer is 4) DAG and IP3.
Step-by-step explanation:
Phospholipase C and Membrane Phospholipids Cleavage
Phospholipase C is an enzyme that plays a crucial role in the process of signal transduction within cells. When activated, it specifically targets and cleaves the membrane phospholipid known as phosphatidylinositol 4,5-bisphosphate (PIP₂) to form two important second messengers: diacylglycerol (DAG) and inositol triphosphate (IP3). These second messengers are pivotal in the signaling pathways that regulate numerous cellular activities, including protein expression, cellular metabolism, and cell growth.
DAG is retained within the plasma membrane and has the vital function of activating protein kinase C (PKC), which in turn phosphorylates proteins on their serine and threonine residues, influencing their activity and function. Concurrently, IP3 is soluble and diffuses into the cytoplasm, where it binds to ligand-gated calcium channels on the endoplasmic reticulum. This binding triggers the release of calcium ions (Ca²⁺) into the cytoplasm, contributing further to the downstream signaling events that follow.
In response to the question, phospholipase C cuts membrane phospholipids into diacylglycerol (DAG) and inositol triphosphate (IP3), making the correct answer 4) DAG and IP3.