Carnitine is indispensable for energy metabolism, since it enables activated fatty acids to enter the mitochondria, where they are broken down via β-oxidation. Carnitine is probably present in all animal species, and in numerous micro-organisms and plants. In mammals, carnitine homoeostasis is maintained by endogenous synthesis, absorption from dietary sources and efficient tubular reabsorption by the kidney. This review aims to cover the current knowledge of the enzymological, molecular, metabolic and regulatory aspects of mammalian carnitine biosynthesis, with an emphasis on the human and rat.
Abbreviations used: ALDH9, aldehyde dehydrogenase 9; BBD, γ-butyrobetaine dioxygenase; CDSP, primary systemic carnitine deficiency; (H)TML, (3-hydroxy-)N6-trimethyl-lysine; HTMLA, HTML aldolase; JVS, juvenile steatosis; OCTN2, organic cation transporter 2; PPARα, peroxisome-proliferator-activated receptor α; SHMT, serine hydroxymethyltransferase; TMABA, 4-N-trimethylaminobutyraldehyde; TMABA-DH, TMABA dehydrogenase; TMLD, TML dioxygenase.