A Gs-coupled receptor on a hepatocyte is activated. The effector pathway that is directly activated by GTP-bound Gsα is:

• A Phospholipase C-β, generating IP3 and DAG
• B Phosphodiesterase, degrading cAMP to 5'-AMP
• C Adenylyl cyclase, converting ATP to cAMP ✓
• D Tyrosine kinase domain of the receptor

Explanation

Gsα (stimulatory G-protein alpha subunit) with bound GTP directly activates adenylyl cyclase (AC), which catalyses the conversion of ATP to cyclic AMP. cAMP then activates PKA. Phospholipase C-β is activated by Gq-coupled receptors (not Gs). Phosphodiesterase degrades cAMP and is not activated by Gsα. Tyrosine kinase activity is characteristic of receptor tyrosine kinases (e.g., insulin receptor), not GPCRs.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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