Comparison of plasma membrane FABP and mitochondrial isoform of aspartate aminotransferase from rat liver.
A relationship between plasma membrane fatty acid binding protein (FABPpm), a putative membrane transporter for long-chain fatty acids, and the mitochondrial isoform of aspartate aminotransferase (m-AspAT) has been reported. Accordingly, we have compared the chemical and immunological properties of rat liver m-AspAT with those of rat liver FABPpm isolated by two procedures: 1) detergent solubilization of the membranes followed by purification via fatty acid affinity chromatography (FABP-1) or 2) salt extraction of the membranes and subsequent purification by high-performance liquid chromatography (HPLC; FABP-2). Comparison of the three protein preparations revealed no differences with respect to NH2-terminal amino acid sequence, amino acid composition, peptides from tryptic digests, AspAT enzymatic activity, isoelectric point, mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), retention on five different HPLC columns, and immunoprecipitation and immunoblotting of SDS-PAGE separated proteins with polyclonal antisera. Examination of the proteins by nondenaturing PAGE showed a consistent second band in FABP-1 and FABP-2 not always present in m-AspAT. However, whenever present, this band was immunoreactive with antibodies to both m-AspAT and FABP-1. Hence, FABP-1 and FABP-2 are indistinguishable from one another. They are also at least closely related, if not identical, to m-AspAT.
Stump
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Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029.
Zhou
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Berk
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D000595:Amino Acid Sequence; D000818:Animals; D001219:Aspartate Aminotransferases / Q000737:chemistry / Q000302:isolation & purification*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification*; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005779:Immunodiffusion; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; C493320:Fabp1 protein, mouse; C493321:Fabp1 protein, rat; C493405:Fabp2 protein, mouse; C493407:Fabp2 protein, rat; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D007527:Isoenzymes; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D001219:Aspartate Aminotransferases