Carnitine octanoyltransferase

CARNITINE ACETYLTRANSFERASE CARNITINE OCTANOYLTRANSFERASE CARNITINE PALMITOYLTRANSFERASE... 

The products of peroxisomal P-oxidation in animals are acetyl-CoA, NADH, and chain-shortened acyl-CoAs that are completely degraded in mitochondria. Chain-shortened acyl residues and acetyl groups are thought to leave peroxisomes as acylcamitines that can be formed from acyl-CoAs by peroxisomal carnitine octanoyltransferase and/or carnitine acetyltransferase [25,26]. The conversion of acyl-CoAs to acylcamitines regenerates CoA in peroxisomes as does the hydrolysis of acyl-CoAs by thioesterases. The recycling of cofactors in peroxisomes and the transport of substrates, cofactors, and metabolites across the peroxisomal membrane are aspects of p-oxidation that remain to be investigated. 

NicA Bhaird, N. Ramsay, R. (1992) Biochem J 2%, 637-640 Malonyl-CoA inhibition of peroxisomal carnitine octanoyltransferase. 

Carnitine acyltransferases (CATs) are a family of enzymes that transport fatty acyl-CoAs across membranes in a range of organelles so that the CoA-esters can be met -olized further. The CAT enzyme involved depends on the lengfli of the fatty acid moeity to be transported. Carnitine acetyltransferase acts with acetyl-CoA as substrate while mitochondrial carnitine palmitoyltransferase (CPT) I and CPT D, transport long-chain acyl groups into the mitochondrial matrix, where they undergo -oxidation. Peroxisomal carnitine octanoyltransferase (COT) transports medium-chain fatty acids across the membrane in peroxisomes in a similar way to CPT I in mitochondria. Peroxisomal P-oxi-dation may account for a significant proportion of all hver fatty acid oxidation and COT is involved in this process. ... 

Pnicessuig of Carnitine Octanoyltransferase PRE-mRNAs By CIS and rraws-Splicing... 

COT, Carnitine Octanoyltransferase. RT-PCR, reverse transcriptase-polymerase chain reaction. ESE, exonic splicing enhancer. PL, plasmid polylinker region. 

Chatterjee, B., Song, C.S., Kim, J.M. Roy, A.K.. (i9SS) Biochemistry 27, 9000-9006. Cloning, sequencing, and regulation of rat liver carnitine octanoyltransferase transcription stimulation of the enzyme during peroxisome proliferation. 

Carnitine acyltransferases in mitochondria, peroxisomes and the endoplasmic reticulum are different gene products and serve different metabolic fimctions in the cell. Here we summarize briefly evidence that carnitine octanoyltransferase (COT) from the peroxisomes and carnitine palmitoyltransferase II (CPT-II) from the mitochondria (both matrix facing enzymes) differ kinetically and demonstrate that they differ in their sensitivity to conformationally constrained inhibitors that mimic the reaction intermediate. Medium chain inhibitors are 15 times more effective on COT than on CPT-II and long chain inhibitors, such as hemipalmitoylcamitinium, 80 times more effective on the mitochondrial enzyme. Thus, it may be possible to develop inhibitors to inhibit mitochondrial P-oxidation with minimal effects on peroxisomal P-oxidation and other acyl-CoA dependent reactions. 

Clarke, P.R.H. Bieber, L.L. (1981)/. Biol. Chem. 256, 9861-9868. Isolation and purification of mitochondrial carnitine octanoyltransferase activities from beef heart. 

Searching sequence databases with PASTA turned up no other proteins homologous to CPTII except other carnitine acyl transferases such as carnitine acetyltransferase, choline acetyltransferase or carnitine octanoyltransferase. 

PROCESSING OF CARNITINE OCTANOYLTRANSFERASE PRE-mRNAs BY CIS AND rRAAS-SPLICING... 

Cronin, C.N. (1997) Eur. J. Biochem. 247,1029-1037. cDNA cloning, recombinant expression, and site-directed mutagenesis of bovine Uver carnitine octanoyltransferase. 

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