IP3 and DAG

The video explores an alternative function of G proteins, focusing on the role of PIP2 in increasing intracellular calcium ion concentration. It explains the mechanism of enzyme activation, highlighting the production of IP3 and its impact on calcium release from the endoplasmic reticulum. The video also discusses calmodulin's role in activating protein kinase and the subsequent cellular response. Additionally, it covers the function of diacylglycerol in activating protein kinase C, emphasizing the importance of phosphorylation in cellular processes.

What is the primary role of PIP2 in the G protein signaling pathway?

• To activate adenylate cyclase

• To decrease intracellular calcium ion concentration

• To play a central role in increasing intracellular calcium ion concentration

• To inhibit phospholipase C

Which enzyme is activated by the G protein in this alternative pathway?

• Adenylate cyclase

• Phospholipase C

• Protein kinase A

• Calmodulin

What are the two products formed when PIP2 is hydrolyzed by phospholipase C?

• IP3 and diacylglycerol

• ATP and cAMP

• NADH and FADH2

• Glucose and fructose

What happens when IP3 binds to its receptor on the endoplasmic reticulum?

• Sodium ions are released into the cytoplasm

• Calcium channels open, releasing calcium ions into the cytoplasm

• Potassium ions are absorbed into the endoplasmic reticulum

• Chloride ions are released into the cytoplasm

How does calcium function as a second messenger in the cell?

• By inhibiting phosphatases

• By binding to DNA and altering gene expression

• By binding to calmodulin and activating calmodulin-dependent protein kinase

• By directly phosphorylating proteins

What is the role of calmodulin in the calcium signaling pathway?

• To synthesize diacylglycerol

• To inhibit calcium release from the endoplasmic reticulum

• To bind calcium and activate calmodulin-dependent protein kinase

• To degrade IP3

What is the function of diacylglycerol in the signaling pathway?

• To increase intracellular sodium concentration

• To inhibit phospholipase C

• To bind to calmodulin

• To activate protein kinase C