New insights into the mitochondrial carnitine palmitoyltransferase enzyme system.
Dissection of the mitochondrial carnitine palmitoyltransferase (CPT) enzyme system in terms of its structure/function relationships has proved to be a formidable task. Although no one formulation has gained universal agreement we believe that the weight of evidence supports a model with the following features: a) in any given tissue CPT I and CPT II are distinct proteins; b) CPT I, unlike CPT II, is detergent labile; c) within a species CPT II is expressed body wide, whereas CPT I exists as tissue specific isoforms; d) malonyl-CoA and other CPT I inhibitors probably interact at the catalytic center of the enzyme, not with a regulatory subunit. The amino acid sequences of rat and human CPT II (deduced from cDNA clones) show them to be similar proteins (greater than 80% identity) but encoded by mRNAs of significantly different sizes. Efforts to clone and sequence the cDNA for rat liver CPT I are presently underway.
McGarry
J D
JD
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235.
Sen
A
A
Esser
V
V
Woeltje
K F
KF
Weis
B
B
Foster
D W
DW
D000595:Amino Acid Sequence; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008316:Malonyl Coenzyme A / Q000378:metabolism / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology*; D008929:Mitochondria, Heart / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D008931:Mitochondria, Muscle / Q000201:enzymology; D008954:Models, Biological; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship
D007527:Isoenzymes; D008316:Malonyl Coenzyme A; D002334:Carnitine O-Palmitoyltransferase