True about G protein coupled receptors is:
Correct Answer: G proteins act as inhibitory and excitatory because of difference in alpha subunit
Description: Ans. (C) G proteins act as inhibitory and excitatory because of difference in alpha subunit(Ref: KDT 8th/e p54)* G proteins are so-called because they bind the guanine nucleotides GDP and GTP. They are heterotrimers (i.e., made of three different subunits)* The three subunits are: Ga, Gb and Gg.* In the inactive state G protein has GDP bound to its Ga subunit.* When a hormone or other ligand binds to the associated receptor (GPCR), the GDP is exchanged for GTP.* GTP activates Ga causing it to dissociate from GbGg (which remain linked as a dimer).* Activated Ga in turn activates an effector molecule like adenylyl cyclase, which catalyzes the conversion of ATP to the "second messenger" cyclic AMP).* Gs, Gi and Gq are different types of G-proteins due to different a-subunits.* Gs and Gq are stimulatory whereas Gi is inhibitory G-protein.
Category:
Pharmacology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now