Where are fatty acids synthesized?

Fatty acid synthesis occurs within the cytoplasm and endoplasmic reticulum of liver cells and fat cells. This occurs in 3 main steps: the citrate shuttle, acetyl-CoA carboxylase, and the fatty acid synthase complex. The citrate shuttle transports acetyl-CoA from the mitochondria to the cytosol for fatty acid synthesis (via CACT). Acetyl-CoA carboxylase is the rate limiting enzyme which creates the formation of malonyl-CoA from acetyl-CoA. Biotin is a cofactor necessary for this reaction to occur. Acetyl-CoA is stimulated by insulin and inhibited by glucagon and epinephrine. The fatty acid synthase complex is responsible for the synthesis from acetyl-CoA and malonyl-CoA, with the addition of NADPH, to form long-chain saturated fatty acids. Malonyl-CoA acts as the activated donor of acetyl molecules during fatty acid synthesis.