Biochemistry : Second Messengers

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #21 : Second Messengers

In a G protein-coupled receptor, the activation of an inhibitory G protein will lead to which of the following?

Possible Answers:

The decrease in cAMP

Adenyl cyclase hydrolysis of ATP

An inactivated alpha subunit of the G protein 

Downstream activation of PKA

The activation of adenylyl cyclase

Correct answer:

The decrease in cAMP

Explanation:

With an inhibitory G protein, the binding of a ligand and stimulation of the receptor will activate the alpha subunit of the G protein, however since it is an inhibitory G protein, it will not go on to activate adenyl cyclase. With no activation of Adenyl cyclase it will lead to decrease cAMP and other secondary messengers. 

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