Generation of Malonyl-Coa for the fatty acid synthesis
Production of the Malony-Coa happens via Acetyl-CoA Carboxylase enzyme (ACC - Synthesis of Malonyl-CoA). The synthesis requires a high energy state, which is generated by the ATP excess by the TCA cycle in the mitochondria (Figure 1.)
The "production" of Malonyl-CoA starts in the mitochondria with the excess amount of Citrate from the TCA cycle.
Citrate is transported into the cytosol through the citrate shuttle. In the cytosol, citrate changes back to Acetyl-CoA in an ATP-dependent process.
Acetyl-CoA is being used by the ACC enzyme in the second enzymatic step of the carboxylase reaction, followed by the production of the Malonyl-Coa molecule.
The 3C atom-containing molecule the fatty acid synthesis can be initiated now.