Review Note

GPCR with Gαi G-Protein: Step-by-Step

1. Ligand Binding: A ligand (e.g., hormone or neurotransmitter) binds to the GPCR on the cell membrane.
2. Receptor Activation: The GPCR undergoes a conformational change, activating the associated Gαi protein.
3. GTP Exchange: Gαi exchanges GDP for GTP, causing it to dissociate from the Gβγ subunits.
4. Effector Activation: The activated Gαi-GTP complex binds to and {{c1::inhibits}} adenylate cyclase, reducing cAMP levels.
5. Decrease in cAMP: With lower cAMP, there is reduced activation of {{c2::protein kinase A (PKA)}}, leading to decreased phosphorylation of target proteins.
6. Termination: Gαi hydrolyzes GTP to GDP, reassociating with Gβγ, and returns to its inactive state, ending the signaling.