Plasma membrane fatty acid-binding protein and mitochondrial glutamic-oxaloacetic transaminase of rat liver are related.
The hepatic plasma membrane fatty acid-binding protein (h-FABPPM) and the mitochondrial isoenzyme of glutamic-oxaloacetic transaminase (mGOT) of rat liver have similar amino acid compositions and identical amino acid sequences for residues 3-24. Both proteins migrate with an apparent molecular mass of 43 kDa on SDS/polyacrylamide gel electrophoresis, have a similar pattern of basic charge isomers on isoelectric focusing, are eluted similarly from four different high-performance liquid chromatographic columns, have absorption maxima at 435 nm under acid conditions and 354 nm at pH 8.3, and bind oleate with a Ka approximately 1.2-1.4 x 10(7) M-1. Sinusoidally enriched liver plasma membranes and purified h-FABPPM have GOT enzymatic activity; the relative specific activities (units/mg) of the membranes and purified protein suggest that h-FABPPM constitutes 1-2% of plasma membrane protein in the rat hepatocyte. Monospecific rabbit antiserum against h-FABPPM reacts on Western blotting with mGOT, and vice versa. Antisera against both proteins produce plasma membrane immunofluorescence in rat hepatocytes and selectively inhibit the hepatocellular uptake of [3H]oleate but not that of [35S]sulfobromophthalein or [14C]taurocholate. The inhibition of oleate uptake produced by anti-h-FABPPM can be eliminated by preincubation of the antiserum with mGOT; similarly, the plasma membrane immunofluorescence produced by either antiserum can be eliminated by preincubation with the other antigen. These data suggest that h-FABPPM and mGOT are closely related.
Department of Medicine (Hepatic Research Group), Mount Sinai School of Medicine, New York, NY 10029.
P D
PD
Berk
H
H
Wada
Y
Y
Horio
B J
BJ
Potter
D
D
Sorrentino
S L
SL
Zhou
L M
LM
Isola
D
D
Stump
C L
CL
Kiang
S
S
Thung
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001219:Aspartate Aminotransferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D007700:Kinetics; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008930:Mitochondria, Liver / Q000201:enzymology*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism; D051381:Rats
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009829:Oleic Acids; D019301:Oleic Acid; D001219:Aspartate Aminotransferases