CPT11

CPT11, also known as Carnitine Palmitoyltransferase 1A, is an enzyme primarily found in the mitochondria of liver cells. It plays a crucial role in fatty acid metabolism, specifically in the process of beta-oxidation, which is the breakdown of fatty acids to produce energy. CPT11 is the rate-limiting enzyme in this pathway, meaning its activity determines the overall speed of fatty acid oxidation.

The enzyme catalyzes the first committed step in the transport of long-chain fatty acids from the cytoplasm into the mitochondrial matrix. It converts long-chain acyl-CoAs into acylcarnitines by attaching a carnitine molecule. This acylcarnitine can then be transported across the inner mitochondrial membrane by the carnitine-acylcarnitine translocase (CACT) system. Once inside the matrix, the fatty acid is transferred back to CoA by Carnitine Palmitoyltransferase 2 (CPT2), and then undergoes beta-oxidation.

CPT11 is tightly regulated and its activity is influenced by factors such as malonyl-CoA, a molecule produced during fatty acid synthesis. High levels of malonyl-CoA inhibit CPT11, preventing fatty acids from entering the mitochondria for oxidation when energy stores are sufficient. This reciprocal regulation ensures that fatty acid synthesis and breakdown are coordinated. Genetic mutations in the gene encoding CPT11 can lead to a rare metabolic disorder known as very long-chain acyl-CoA dehydrogenase deficiency (VLCAD deficiency), although this is more commonly associated with mutations in the gene for VLCAD itself. Understanding CPT11's function is vital for comprehending energy homeostasis and the development of metabolic diseases.