Question

Acetly CoA, the cytoplasmic substrate for FA synthesis, is formed in the mito. The inner mitochondiral membrane is impermeable to Acetly coA. What is the form in which the carbon of Acetyl CoA is transpotered into the cytoplasm?

Answer 1

The carbon from Acetyl CoA is transported into the cytoplasm primarily in the form of citrate, which can cross the mitochondrial membrane. Once in the cytoplasm, citrate is converted back to acetyl CoA, available for fatty acid synthesis.

Step-by-step explanation:

The form in which the carbon of Acetyl CoA is transported into the cytoplasm from the mitochondria is primarily as citrate. Since the inner mitochondrial membrane is impermeable to Acetyl CoA, it is first combined with oxaloacetate to form citrate, which can cross the membrane. Once in the cytoplasm, citrate is converted back to acetyl CoA by the enzyme citrate lyase, which releases oxaloacetate and acetyl CoA. This acetyl CoA then becomes available for fatty acid synthesis in the cytoplasm. Alternatively, acetyl CoA can be transported out of the mitochondria in the form of acetylcarnitine, but citrate is the primary molecule used for the transport of acetyl CoA for lipogenesis.