Biosignaling - G-protein-coupled Receptors PLC, DAG, & IP3

The video tutorial explains the G protein-coupled receptor pathways, focusing on the divergence from the adenylate cyclase pathway to the phospholipase C pathway. It details the signal transduction mechanism, the role of phospholipase C in hydrolyzing PIP2 into DAG and IP3, and the subsequent release of calcium ions from the endoplasmic reticulum. The activation of protein kinase C by DAG and calcium is discussed, leading to a phosphorylation cascade that results in a cellular response.

What is the main difference between the first pathway and the one involving phospholipase C?

• The first pathway does not involve G protein-coupled receptors.

• Both pathways involve the same enzymes.

• The first pathway involves adenylyl cyclase activation.

• The first pathway involves phospholipase C activation.

What happens when a hormone binds to the G protein-coupled receptor in this pathway?

• The receptor releases calcium ions.

• The receptor activates adenylyl cyclase.

• The receptor undergoes a conformational change.

• The receptor is degraded.

What are the products of PIP2 hydrolysis by phospholipase C?

• NADH and FADH2

• DAG and IP3

• ATP and cAMP

• GTP and GDP

How does IP3 contribute to the signaling pathway?

• It activates adenylyl cyclase.

• It binds to a receptor on the endoplasmic reticulum, releasing calcium.

• It remains in the membrane to activate protein kinase C.

• It is converted into ATP.

What role does DAG play in the activation of protein kinase C?

• DAG activates adenylyl cyclase.

• DAG releases calcium from the endoplasmic reticulum.

• DAG recruits and partially activates protein kinase C.

• DAG inhibits protein kinase C.

What additional factor is required for the full activation of protein kinase C?

• ATP

• Calcium ions

• GTP

• cAMP

What is the result of the phosphorylation cascade initiated by protein kinase C?

• A decrease in cellular response

• Deactivation of G protein-coupled receptors

• A cellular response through activation of various proteins

• Inhibition of phospholipase C