Cloning of human acetyl-CoA carboxylase-beta and its unique features.
Acetyl-CoA carboxylase, which has a molecular mass of 265 kDa (ACC-alpha), catalyzes the rate-limiting step in the biosynthesis of long-chain fatty acids. In this study we report the complete amino acid sequence and unique features of an isoform of ACC with a molecular mass of 275 kDa (ACC-beta), which is primarily expressed in heart and skeletal muscles. In these tissues, ACC-beta may be involved in the regulation of fatty acid oxidation, rather than fatty acid biosynthesis. ACC-beta contains an amino acid sequence at the N terminus which is about 200 amino acids long and may be uniquely related to the role of ACC-beta in controlling carnitine palmitoyltransferase I activity and fatty acid oxidation by mitochondria. If we exclude this unique sequence at the N terminus the two forms of ACC show about 75% amino acid identity. All of the known functional domains of ACC are found in the homologous regions. Human ACC-beta cDNA has an open reading frame of 7,343 bases, encoding a protein of 2,458 amino acids, with a calculated molecular mass of 276,638 Da. The mRNA size of human ACC-beta is approximately 10 kb and is primarily expressed in heart and skeletal muscle tissues, whereas ACC-alpha mRNA is detected in all tissues tested. A fragment of ACC-beta cDNA was expressed in Escherichia coli and antibodies against the peptide were generated to establish that the cDNA sequence that we cloned is that for ACC-beta.
Ha
J
J
Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA.
Lee
J K
JK
Kim
K S
KS
Witters
L A
LA
Kim
K H
KH
D000103:Acetyl-CoA Carboxylase / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D016366:Open Reading Frames; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D046911:Macromolecular Substances; D012333:RNA, Messenger; D011994:Recombinant Proteins; D002334:Carnitine O-Palmitoyltransferase; D000103:Acetyl-CoA Carboxylase