Autoantibodies in the sera of patients with pernicious anemia recognize, in addition to the α subunit of the gastric H+/K+-ATPase, an abundant gastric microsomal glycoprotein of apparent M(r) 60,000-90,000. Herein we have colocalized the glycoprotein and the α subunit of the gastric H+/K+-ATPase to the tubulovesicular membranes of the parietal cell by immunogold electron microscopy. Moreover, the glycoprotein and the α subunit were coimmunoprecipitated, and copurified by immunoaffinity chromatography, with an anti-glycoprotein monoclonal antibody. The pig glycoprotein was purified by chromatography on tomato lectin-Sepharose, and five tryptic peptides from the purified glycoprotein were partially sequenced. The complete amino acid sequence, deduced from the nucleotide sequence of overlapping cDNA clones, showed 33% similarity to the sequence of the β subunit of the pig kidney Na+/K+-ATPase. We therefore propose that the 60- to 90-kDa glycoprotein autoantigen is the β subunit of the gastric H+/K+-ATPase and that the α and β subunits of the proton pump are major targets for autoimmunization in autoimmune gastritis.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 5 Sep 1990|
- acid secretion
- organ-specific autoimmunity
- pernicious anemia