Carnitine octanoyltransferase (CROT or COT), also known as octanoyl-CoA: L-carnitine O-octanoyltransferase, medium-chain/long-chain carnitine acyltransferase, and carnitine medium-chain acyltransferase, is a carnitine acyltransferase belonging to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups that catalyzes the reversible transfer of fatty acyl groups between CoA and carnitine. Carnitine octanoyltransferase (CROT or COT) facilitate the transport of medium- and long-chain fatty acids through the peroxisomal and mitochondrial membranes. It is physiologically inhibited by malonyl-CoA. COT also has functions in efficiently converting one of the end products of the peroxisomal beta-oxidation of pristanic acid, 4, 8-dimethylnonanoyl-CoA, to its corresponding carnitine ester.