Phospholipase C, IP3, DAG, and Ca2+

The video provides a concise overview of phospholipase C, its activation by G protein-coupled receptors, and its role in bio signaling. It explains the structure of phosphatidylinositol 4,5-bisphosphate and the mechanism of phospholipase C, leading to the production of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol. The video also discusses the function of IP3 in calcium signaling and the role of diacylglycerol in activating protein kinase C.

What is the primary role of phospholipase C in G protein-coupled receptor signaling?

• To activate adenylate cyclase

• To bind calcium ions

• To cleave PIP2 into IP3 and DAG

• To synthesize ATP

Which component of PIP2 is cleaved by phospholipase C?

• The arachidonic acid

• The phosphate group

• The inositol ring

• The glycerol backbone

What is the function of the hydroxyl group in the mechanism of phospholipase C?

• Acts as a nucleophile

• Stabilizes the enzyme structure

• Binds to calcium ions

• Forms a hydrogen bond

What is the significance of inositol 1,4,5-trisphosphate (IP3) in cellular signaling?

• It inhibits protein kinase C

• It degrades cyclic AMP

• It phosphorylates proteins directly

• It acts as a second messenger to release calcium from the ER

How does IP3 affect calcium ion concentration in the cytosol?

• It has no effect on calcium ion concentration

• It increases calcium ion concentration

• It decreases calcium ion concentration

• It binds calcium ions to the cell membrane

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

• It transports protein kinase C to the nucleus

• It acts as a substrate for protein kinase C

• It serves as a coenzyme for protein kinase C

• It inhibits protein kinase C

Which of the following is required for the activation of protein kinase C?

• ATP

• GTP

• Calcium ions

• Cyclic AMP

What is the primary function of protein kinase C in cellular signaling?

• To transport ions across the membrane

• To phosphorylate serine and threonine residues

• To synthesize DNA

• To degrade proteins

Why is protein kinase C confined to the membrane?

• It binds to membrane lipids

• It is synthesized in the membrane

• It is inhibited by cytosolic proteins

• It requires DAG for activation

What is the relationship between DAG and the polarity of the membrane?

• DAG is polar and diffuses into the cytosol

• DAG is nonpolar and remains in the membrane

• DAG decreases membrane polarity

• DAG increases membrane polarity