Question

Discuss in detail how Trimeric G-protein signaling pathways would be influenced by the following:

A)Please describe the molecular switches that are applied in G-protein coupled receptor signaling pathways, and compare the molecular switches in detail.

B)Consider cells injected with a small molecule that blocks the association of the G-Protein Coupled-Receptor with its Trimeric G-protein:

-What would be the effect of this small molecule on the activity of the Trimeric G-proteins in this cell?

-Why? Be specific about how the receptor influences the Trimeric G-protein

C)Consider cells treated with a drug that enhances the ability of the Trimeric G-protein to associate with GTP:

-How would this drug affect the concentration of Ca+ in cells?

Answer 1

A) G-protein couple receptors have mainly 2 types of switches:rotamer toggle switch and ligand induced ionic locks.

B) If cells are injected with a molecule that blocks the association of GPCR with trimeric G protein then they will no longer be able activate the cascade of reactions that should have been activated by appropriate stimulus.
The association of GPCR with trimeric G protein causes confirmational change in both,in the trimeric G protein the alpha and beta subunit are freed from the gamma subunit of this protein due to phosphorylation of alpha subunit.Now the alpha- beta pair and gamma subunit each intiates different cascade of reactions.

C) A drug that would enhance the activity of Trimeric G protein then that would increase the concentration of calcium inside the cytoplasm.

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