Category: transport
Transports long-chain fatty acyl groups across the inner mitochondrial membrane for β-oxidation. Outer membrane: CPT1 transfers the acyl group from CoA to carnitine, producing acyl-carnitine. Inner membrane: CACT (carnitine-acylcarnitine translocase) exchanges acyl-carnitine for free carnitine. Inner matrix: CPT2 transfers the acyl group back to CoA, regenerating intramitochondrial acyl-CoA for β-oxidation. CPT1 is the regulatory step — inhibited by malonyl-CoA (the link to fatty acid biosynthesis: high malonyl-CoA → FA synthesis ON + β-oxidation OFF). Carnitine deficiency (primary genetic or secondary to valproate/pivalate antibiotics/hemodialysis) presents as hypoketotic hypoglycemia + cardiomyopathy + skeletal myopathy. Levocarnitine supplementation is therapeutic.