Lecture on IP3 Pathway

Overview

• IP3 Pathway: Involves first and second messenger responses leading to a cellular response.

First Messenger

• Definition: An extracellular molecule/ligand (e.g., hormone).
• Process: Binds to a G-protein coupled receptor.

Activation Process

1. First Messenger Activation: Triggers the second messenger response.
2. Second Messengers Involved:
   • IP3 (Inositol Triphosphate)
   • Diacylglycerol (DAG)
   • Calcium

PIP2 as a Precursor

• Molecule: Phosphatidylinositol 4,5-bisphosphate (PIP2).
• Role: Precursor for DAG and IP3.
• Cleavage: PIP2 splits into DAG and IP3.

Key Components

G-Protein Coupled Receptor

• Function: Becomes activated by ligand binding.
• Effect: Activates phospholipase C.

Phospholipase C

• Action: Cleaves PIP2 into IP3 and DAG.

Endoplasmic Reticulum and Calcium Release

• IP3 Role: Binds to and opens IP3 calcium channel on the ER.
• Calcium Movement: Flows from the ER into the cytosol, increasing cytosolic calcium levels.

Activation of Protein Kinase C

• Involved Molecules: DAG and Calcium.
• Result: Activation of Protein Kinase C (PKC).
• Function of PKC: Phosphorylates target proteins, leading to a cellular response.

Summary

• First Messenger: Extracellular ligand binds to receptor.
• Second Messengers: PIP2 cleaves to IP3 and DAG; calcium released from ER.
• Cellular Response: Activation of PKC and phosphorylation leading to cellular changes.

Conclusion

• Quick overview of the IP3 pathway.
• Encouragement to like and subscribe for more lessons.