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Carnitine
Quaternary amine synthesized from lysine and methionine that, as part of the carnitine palmitoyltransferase shuttle, transports long-chain fatty acids across the inner mitochondrial membrane for β-oxidation.
Also: L-carnitine, γ-trimethyl-β-hydroxybutyrobetaine
Acyl-CoAs are conjugated to carnitine by CPT1 on the outer mitochondrial membrane, translocated by CACT, and reconverted to acyl-CoA by CPT2 on the inner membrane. Primary carnitine deficiency (OCTN2/SLC22A5 mutations) causes hypoketotic hypoglycemia and cardiomyopathy treatable with high-dose carnitine. Gut microbial conversion of carnitine (and choline) to TMAO has been linked to cardiovascular risk in some studies.
How one textbook covers it
Modern Nutrition in Health and Disease, 12th ed. — Ch 29: Carnitine
Acyl-CoAs are conjugated to carnitine by CPT1 on the outer mitochondrial membrane, translocated by CACT, and reconverted to acyl-CoA by CPT2 on the inner membrane. Primary carnitine deficiency (OCTN2/SLC22A5 mutations) causes hypoketotic hypoglycemia and cardiomyopathy treatable with high-dose carnitine. Gut microbial conversion of carnitine (and choline) to TMAO has been linked to cardiovascular risk in some studies.
Related terms
CPT1, Lysine, TMAO, β-Oxidation