Carnitine transporters and carnitine acetyltransferase (OCTN2/CrAT)

Carnitine transporters and carnitine acetyltransferase refers to a functional group of proteins essential for carnitine-mediated fatty acid metabolism and mitochondrial energy balance. The primary transporter, Organic cation/carnitine transporter 2 (OCTN2, encoded by SLC22A5), facilitates the sodium-dependent uptake of carnitine into cells and its conservation in the kidneys (UniProt O76082). Carnitine is a vital cofactor required for the transport of long-chain fatty acids into the mitochondrial matrix for beta-oxidation. Carnitine acetyltransferase (CrAT) facilitates the reversible transfer of acetyl groups between CoA and carnitine, playing a critical role in maintaining the mitochondrial acetyl-CoA/CoA ratio and overall metabolic flexibility (UniProt P43155). Dysregulation of these proteins is linked to primary carnitine deficiency, organic acidemias, and metabolic syndromes such as type 2 diabetes and cardiovascular disease (PubMed PMC4162486). Pharmacological modulation of this system is a therapeutic strategy; for instance, the drug meldonium inhibits OCTN2 to shift energy metabolism from fatty acid oxidation to glucose oxidation. This metabolic shift is particularly beneficial in ischemic conditions, where glucose oxidation is more oxygen-efficient than fatty acid oxidation (PubChem CID 123596). Additionally, CrAT is being investigated as a target to improve glucose tolerance by managing the accumulation of acetyl-CoA in the mitochondria.

Other names

SLC22A5OCTN2CrATCarnitine O-acetyltransferaseCATOrganic cation/carnitine transporter 2Solute carrier family 22 member 5

Inhibition of carnitine transport to reduce fatty acid oxidation and shift metabolism toward glucose utilization; buffering of mitochondrial acetyl-CoA levels to maintain metabolic flexibility.