Acetyl-CoA generated in mitochondria cannot cross the inner mitochondrial membrane directly. Which enzyme of the cytosolic shuttle that transfers acetyl units for fatty acid synthesis is also a direct target of insulin-mediated dephosphorylation activation?

• A Citrate synthase
• B Acetyl-CoA synthetase
• C Pyruvate carboxylase
• D ATP citrate lyase ✓

Explanation

The citrate shuttle moves acetyl-CoA out of mitochondria as citrate; cytosolic ATP citrate lyase cleaves it back to acetyl-CoA and oxaloacetate using ATP. Insulin activates ATP citrate lyase by dephosphorylation, coordinating carbon flux into lipogenesis. Citrate synthase is a mitochondrial TCA enzyme and pyruvate carboxylase supplies oxaloacetate for gluconeogenesis, not cytosolic acetyl-CoA generation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.