Carnitine O-acetyltransferase

Carnitine O-acetyltransferase also called carnitine acetyltransferase (CRAT, or CAT) (EC 2.3.1.7) is an enzyme that encoded by the CRAT gene that catalyzes the chemical reaction

acetyl-CoA + carnitine ${\displaystyle \rightleftharpoons }$ CoA + acetylcarnitine

where the acetyl group displaces the hydrogen atom in the central hydroxyl group of carnitine.

Thus, the two substrates of this enzyme are acetyl-CoA and carnitine, whereas its two products are CoA and O-acetylcarnitine. The reaction is highly reversible and does not depend on the order in which substrates bind.

Different subcellular localizations of the CRAT mRNAs are thought to result from alternative splicing of the CRAT gene suggested by the divergent sequences in the 5' region of peroxisomal and mitochondrial CRAT cDNAs and the location of an intron where the sequences diverge. The alternatively splicing of this gene results in three distinct isoforms, one of which contains an N-terminal mitochondrial transit peptide, and has been shown to be located in mitochondria.