Purification and characterization of a fatty-acid-binding protein from the gastric mucosa of rats. Possible identity with heart fatty-acid-binding protein and its parietal cell localization.

Fatty acid-binding protein (FABP) was purified from rat gastric mucosa by successive Sephadex G-75 chromatography, DEAE-cellulose chromatography and HPLC on an RP-2 (Merck) reversed-phase column. The purified stomach FABP migrated as a single band corresponding to an apparent molecular mass of 15 kDa on SDS/PAGE. Stomach FABP appeared to be identical with rat heart FABP, as judged from its electrophoretic mobility, amino acid composition and tryptic peptide map. In addition, the amino acid sequences of two selected tryptic peptides coincided completely with the rat heart FABP sequence deduced from that of cDNA. Stomach FABP showed immunochemical identity with rat heart FABP when tested with an antiserum against rat heart FABP. Immunohistochemically, stomach FABP was specifically stained with anti-(rat heart FABP) serum in parietal cells of the gastric mucosa. The results suggested that the primary structure of stomach FABP is identical with that of rat heart FABP, and showed that stomach FABP is localized in parietal cells of the gastric mucosa.