Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

carnitine O-palmitoyltransferase

Name from literature

carnitine palmitoyltransferase 1a

Pathway from literature

fatty acid metabolism/fatty acid oxidation

Pathway from KEGG

Lipid Metabolism; Fatty acid metabolism; map00071

Cellular Processes; Endocrine System; Adipocytokine signaling pathway; map04920

Cellular Processes; Endocrine System; PPAR signaling pathway; map03320


Human (9606)

Genome localization

11q13.1-q13.2[1374 ], 1p32[1376 ], 19q13.33[126129 ], 22q13.33[1375 ],


Broad specificity to acyl group, over the range C8 to C18; optimal activity with palmitoyl-CoA. cf. EC carnitine O-acetyltransferase and EC carnitine O-octanoyltransferase.

Rate-limiting Description

"Carnitine palmitoyltransferase I is assumed to be rate limiting for beta-oxidation in all tissues." (11356163)

"Hypoxia prevented the known LCFA-induced accumulation of mRNA encoding muscle carnitine palmitoyltransferase I (M-CPT I), an enzyme that catalyzes the rate-limiting step in mitochondrial fatty acid oxidation (FAO)." (11371554)

Regulatory Information

Upstream transcription factor


Regulatory type



"It has also been described as a malonyl-CoA analogue that antagonizes the allosteric inhibitory effect of malonyl-CoA on carnitine palmitoyltransferase I (CPT I), the main regulatory enzyme involved in fatty acid oxidation." (17239528)

regulatory enzyme;

"It has also been described as a malonyl-CoA analogue that antagonizes the allosteric inhibitory effect of malonyl-CoA on carnitine palmitoyltransferase I (CPT I), the main regulatory enzyme involved in fatty acid oxidation." (17239528#14517221#10956641)

transcriptional factor;PGC1(10891)

"a conserved functional PPAR responsive element downstream of the transcriptional start site of the human CPT1A gene is localized; this sequence is fundamental for fatty acids or PGC1-induced transcriptional activation of the CPT1A gene" (16271724#12408750)













Gene ontology

Gene ontology

GO:0006635 (P) fatty acid beta-oxidation [P23786, Q92523, P50416 ];
GO:0004095 (F) carnitine O-palmitoyltransferase activity [P23786, Q92523, Q8TCG5, P50416 ];
GO:0006853 (P) carnitine shuttle [P23786, Q92523 ];
GO:0006810 (P) transport [P50416 ];
GO:0006631 (P) fatty acid metabolic process [Q8TCG5 ];
GO:0046320 (P) regulation of fatty acid oxidation [P23786, Q92523 ];
GO:0016021 (C) integral to membrane [Q92523, Q8TCG5, P50416 ];
GO:0005743 (C) mitochondrial inner membrane [P23786 ];
GO:0005741 (C) mitochondrial outer membrane [Q92523, Q8TCG5, P50416 ];

Tissue expression

Tissue From HPRD

Small intestine [12315 ];
Colon [12315 ];
Ubiquitous [02802 ];
Heart [09065 ];
Testis [12315 ];
Ovary [12315 ];
Liver [02755 ];
Skeletal muscle [09065 ];
Brain [12315 ];

Tissue specificity

Strong expression in kidney and heart, and lower in liver and skeletal muscle [P50416 ];

Strong expression in heart and skeletal muscle. No expression in liver and kidney [Q92523 ];

Expressed predominantly in brain and testis [Q8TCG5 ];

Subcellular localization


mitochondrion [P23786, Q92523, Q8TCG5, P50416 ];

membrane [P23786 ];

Disease relevance


Defects in CPT2 are the cause of carnitine palmitoyltransferase II deficiency (CPT-II deficiency) [MIM:255110, 600649]. CPT-II deficiency is an autosomal recessive disorder characterized by recurrent myoglobinuria, episodes of muscle pain, stiffness, and rhabdomyolysis. These symptoms are triggered by prolonged exercise, fasting or viral infection and patients are usually young adults. In addition to this classical, late-onset, muscular type, a hepatic or hepatocardiomuscular form has been reported in infants. Clinical pictures in these children or neonates include hypoketotic hypoglycemia, liver dysfunction, cardiomyopathy and sudden death [P23786 ];

Defects in CPT2 are the cause of lethal neonatal carnitine palmitoyltransferase II deficiency (CPT-II deficiency) [MIM:608836];
a lethal neonatal form of CPT-II deficiency. This rarely presentation is antenatal with cerebral periventricular cysts and cystic dysplastic kidneys. The clinical variability of the disease is likely attributed to the variable residual enzymatic activity [P23786 ];

Defects in CPT1A are the cause of carnitine palmitoyltransferase I deficiency (CPT-I deficiency) [MIM:255120];
also known as CPT1A deficiency. CPT I deficiency is a rare autosomal recessive metabolic disorder of long-chain fatty acid oxidation characterized by severe episodes of hypoketotic hypoglycemia usually occurring after fasting or illness. Onset is in infancy or early childhood [P50416 ];



P23786; P50416; Q8TCG5; Q92523

Entrez Gene

126129; 1374; 1375; 1376


12315; 09065; 02755; 02802

  Copyright 2009, Center for Bioinformatics 
  Last Modified: 2009-03-24  
  Design by Zhao Min