Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circulating parietal cell autoantibodies, a useful diagnostic marker for autoimmune gastritis and pernicious anaemia, are currently routinely tested by serum immunofluorescence reactivity with frozen sections of rodent stomach. The major molecular targets of these parietal cell autoantibodies have recently been demonstrated to be the alpha- and the beta-subunits of the gastric H+/K(+)-ATPase (proton pump). We have demonstrated that tomato lectin binds specifically to the beta-subunit of the proton pump and concomittantly co-purifies the alpha-subunit. In the present study, we have exploited the latter observation for the development of a diagnostic ELISA for the detection of parietal cell autoantibodies and compared the performance of this assay with an ELISA using crude gastric membranes. The ELISAs were tested on 72 parietal cell autoantibody-positive sera, 72 parietal cell autoantibody-negative sera and 72 disease-control sera. The ELISA using lectin-purified canine proton pump was superior to that using crude canine gastric membranes in that it was about two-fold more sensitive (82% vs. 43%). With an assay sensitivity of 82% and a specificity of 90%, we propose that the ELISA using the lectin-purified proton pump is a rapid, simple, sensitive and specific diagnostic immunoassay for parietal cell autoantibodies.
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PMID:Diagnostic ELISA for parietal cell autoantibody using tomato lectin-purified gastric H+/K(+)-ATPase (proton pump). 131 58

Autoimmune gastritis develops spontaneously in approximately 60% of BALB/c mice thymectomized neonatally. Histologically and clinically it is similar to the atrophic gastritis associated with pernicious anaemia in humans. Here we identified antigenic protein relating to the pathogenesis of autoimmune gastritis in these mice. All sera from 32 thymectomized mice with gastritis contained autoantibodies to the vesicular fraction prepared from rat gastric parietal cells. Immunoblot analysis revealed all of these to react with a 94-kD protein corresponding in molecular mass with the H+/K(+)-ATPase alpha subunit. Some sera were also reactive with 65-85-kD and/or 60-kD proteins, whose sizes correspond to the H+/K(+)-ATPase beta subunit and intrinsic factor, respectively. The finding that immuno-adsorption with these sera resulted in reduction of H+/K(+)-ATPase activity in the vesicular fraction, supported a conclusion of H+/K(+)-ATPase alpha and/or beta subunits as the antigenic proteins. After immunization of normal syngeneic mice with various doses of gastric parietal cells or their vesicular fraction, all sera from animals demonstrating atrophic gastric mucosa with lymphocyte infiltration reacted with the H+/K(+)-ATPase alpha subunit. No antibodies to other proteins were induced even in mice immunized with higher doses of antigen. We therefore conclude that H+/K(+)-ATPase alpha subunit is important as the target antigen in pathogenesis of autoimmune gastritis in neonatally thymectomized mice, probably due to a high affinity for the MHC molecule.
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PMID:Involvement of the H+/K(+)-ATPase alpha subunit as a major antigenic protein in autoimmune gastritis induced by neonatal thymectomy in mice. 132 Oct 13

The alpha and beta subunits of the gastric H+/K(+)-ATPase (proton pump) have been identified as the major molecular targets of parietal cell autoantibodies associated with pernicious anaemia and with murine experimental autoimmune gastritis (EAG) induced by neonatal thymectomy. Recent studies with EAG suggest that the mechanisms of peripheral tolerance and autoimmunity to extrathymic autoantigens are mediated by subsets of "regulator" and "effector" CD4+ T cells, respectively. The persistence of "effector" CD4+ autoreactive T cells in the periphery may be a direct consequence of the delayed developmental expression of the target autoantigen. We hypothesize that cytokines produced by the "regulator" T cells prevent the clonal expansion of the "effector" autoreactive T cells, and that neonatal thymectomy induces organ-specific autoimmunity in genetically susceptible individuals by the reduction of the "regulator" T cell population.
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PMID:Autoimmune gastritis: tolerance and autoimmunity to the gastric H+/K+ ATPase (proton pump). 136 68

Murine autoimmune gastritis, induced by neonatal thymectomy, bears a striking similarity in pathology to the human autoimmune disease, pernicious anemia. Autoantibodies to parietal cells are found in both murine and human diseases. Monoclonal immunoglobulin G autoantibodies, obtained from neonatally thymectomized mice, have previously been shown to recognize two groups of gastric parietal cell antigens. In the present study, it is shown that two of these monoclonal autoantibodies, designated 1H9 and 2B6, are directed against the alpha subunit and beta subunit, respectively, of the gastric hydrogen-potassium-stimulated adenosine triphosphatase (H+,K(+)-ATPase; proton pump). Monoclonal antibody 1H9 showed reactivity by immunoblotting with a 95-kilodalton component of dog gastric tubulovesicular membranes and with a fusion protein containing the hydrophilic domain of the alpha subunit of the H+,K(+)-ATPase. Monoclonal antibody 2B6 reacted by immunoblotting with the 60-90-kilodalton glycoprotein (beta subunit) of the tomato lectin-purified dog H+,K(+)-ATPase and with the 60-90-kilodalton autoantigen purified with human parietal cell autoantibodies. Monoclonal antibody 2B6 also reacted with the deglycosylated 35-kilodalton core protein of the tomato lectin-purified 60-90-kilodalton beta subunit and of the purified 60-90-kilodalton autoantigen. Parietal cell autoantibody-positive sera from 20 mice with experimentally induced gastritis showed reactivity predominantly with the alpha and/or beta subunit of the gastric H+,K(+)-ATPase. Therefore, it is concluded that the major molecules targeted by parietal cell autoantibodies from mice with neonatal thymectomy-induced murine autoimmune gastritis and from humans with pernicious anemia are identical.
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PMID:The parietal cell autoantigens recognized in neonatal thymectomy-induced murine gastritis are the alpha and beta subunits of the gastric proton pump [corrected]. 164 25

Autoimmune gastritis, leading to pernicious anaemia, is an organ-specific autoimmune disease characterized by chronic atrophic gastritis and circulating gastric parietal cell autoantibodies. The parietal cell autoantigens have recently been identified as the alpha and beta subunit of the gastric proton pump (H+, K+ ATPase). Here Paul Gleeson and Ban-Hock Toh discuss how the identification of these gastric parietal cell autoantigens and the development of a mouse model of autoimmune gastritis have paved the way for an understanding of the pathogenesis of the gastric lesion.
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PMID:Molecular targets in pernicious anaemia. 165 72

The occurrence of auto-antibodies in patients with the autoimmune disease pernicious anaemia and in patients with active duodenal ulcers was investigated. In order to characterize antigenic structures, various cellular and subcellular fractions were prepared from pig gastric mucosa and from a homogenate of duodenal mucosa. By means of an enzyme-linked immunosorbent assay and immunoblotting, both the H+,K(+)-ATPase and pepsinogen/pepsin were shown to constitute the major antigens. All of the seven pernicious-anaemia sera that were tested contained auto-antibodies against both antigens, and the epitopes of the H+,K(+)-ATPase were shown to be localized on its cytoplasmic face. In 75% (18/24) of the sera from patients with duodenal ulcers, auto-antibodies were detected when using purified antigens. Six sera reacted with H+,K(+)-ATPase and twelve reacted with pepsinogen, one reacted with both antigens, and four sera reacted with the duodenal mucosal antigen. The occurrence of auto-antibodies indicates that there is a mucosal lesion and that immunological factors may be involved in the pathogenesis of the disease in some patients.
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PMID:The occurrence of auto-antibodies in patients with gastro-duodenal lesions. 169 83

The gastric H+/K(+)-transporting adenosine triphosphatase (H+/K+ ATPase) (proton pump) consists of a catalytic alpha-subunit and a recently proposed 60-90-kDa glycoprotein beta-subunit. Using dog gastric membranes as the antigen, we have produced two murine monoclonal antibodies, 4F11 (IgG1) and 3A6 (IgA), which are specific for the 60-90-kDa glycoprotein. The monoclonal antibodies (1) specifically stained the cytoplasm of unfixed and formalin-fixed dog gastric parietal cells; (2) specifically reacted by ELISA with gastric tubulovesicular membranes; (3) recognised epitopes located on the luminal face of parietal cell tubulovesicular membranes, the site of the proton pump, by immunogold electron microscopy; (4) immunoblotted a 60-90-kDa molecule from tubulovesicular membranes and a 35-kDa component from peptide N-glycosidase-F-treated membrane extracts; (5) immunoblotted the 60-90-kDa parietal cell autoantigen associated with autoimmune gastritis and pernicious anemia, purified by chromatography on parietal cell autoantibody- or tomato-lectin-Sepharose 4B affinity columns, and the 35-kDa protein core of this autoantigen; this autoantigen has amino acid sequence similarity to the beta-subunit of the related Na+/K(+)-transporting adenosine triphosphatase (Na+/K+ ATPase) [Toh et al. (1990) Proc. Natl Acad. Sci. 87, 6418-6422]; (6) co-precipitated a molecule of 95 kDa with the 60-90-kDa molecule from 125I-labelled detergent extracts of dog tubulovesicular membranes; and (7) co-purified the catalytic alpha-subunit of the H+/K+ ATPase with the 60-90-kDa molecule by immunoaffinity chromatography of tubulovesicular membrane extracts on a monoclonal antibody 3A6-Sepharose 4B column, indicating a physical association between the two molecules. These results provide further evidence that the 60-90-kDa glycoprotein is the beta-subunit of the gastric H+/K+ ATPase. We conclude that the monoclonal antibodies specifically recognise luminal epitopes on the 35-kDa core protein of the 60-90-kDa beta-subunit of the gastric proton pump, a major target molecule in autoimmune gastritis and pernicious anaemia. These monoclonal antibodies will be valuable probes to study the structure and function of this associated beta-subunit, as well as the ontogeny of the gastric proton pump.
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PMID:Monoclonal antibodies specific for the core protein of the beta-subunit of the gastric proton pump (H+/K+ ATPase). An autoantigen targetted in pernicious anaemia. 170 13

The prevalence and development of antibodies to H+,K+-ATPase were investigated with a sensitive enzyme-linked immunosorbent assay in 86 patients with autoimmune atrophic gastritis (type A). Sixty-nine of the patients had pernicious anemia, and 17 had simple atrophic gastritis. Elevated titers were found in 93% of pernicious anemia probands. Women had higher levels than men: 3.24 versus 1.58 U/l (p = 0.002) (upper reference limit, 0.55 U/l). The antibody levels did not change over 1-4 years, but a gradual decrease in titers over decades was observed. All patients with pernicious anemia had low levels of pepsinogen A, a product of the gastric chief and mucous neck cells (median, 8.5 micrograms/l; reference range, 10-90 percentile, 64.4-195.5 micrograms/l), and elevated serum gastrin values (greater than 55 pmol/l) were found in 87%. Serum pepsinogen A, but not serum gastrin, correlated with H+,K(+)-ATPase antibody titers (r = 0.35, p = 0.01). In the 17 cases with simple atrophic gastritis, H+,K(+)-ATPase antibodies correlated inversely with fundic mucosal gland destruction. The data indicate that H+,K(+)-ATPase antibody titers reflect the immune responsiveness of a given patient as well as the antigenic amount, dependent on the degree of mucosal destruction and the duration of the disease.
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PMID:H+,K-ATPase antibodies in autoimmune gastritis: observations on the development of pernicious anemia. 184 12

Autoantibodies in the sera of patients with pernicious anemia recognize, in addition to the alpha subunit of the gastric H+/(+)-ATPase, an abundant gastric microsomal glycoprotein of apparent Mr 60,000-90,000. Herein we have colocalized the glycoprotein and the alpha subunit of the gastric H+/K(+)-ATPase to the tubulovesicular membranes of the parietal cell by immunogold electron microscopy. Moreover, the glycoprotein and the alpha 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 beta subunit of the pig kidney Na+/K(+)-ATPase. We therefore propose that the 60- to 90-kDa glycoprotein autoantigen is the beta subunit of the gastric H+/K(+)-ATPase and that the alpha and beta subunits of the proton pump are major targets for autoimmunization in autoimmune gastritis.
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PMID:The 60- to 90-kDa parietal cell autoantigen associated with autoimmune gastritis is a beta subunit of the gastric H+/K(+)-ATPase (proton pump). 197 21

Using isolated cells and subcellular fractions from pig gastric mucosa, antigenic structures with specific binding of IgG from sera of patients with auto-immune atrophic gastritis were characterized by means of immunoblotting and enzyme-linked immunosorbent assay. In immunoblotting experiments using mucosal cells as the antigen source, two dominating bands of 94 and 41 kDa were found. The two major antigens were identified as the H,K-ATPase (94 kDa), which constitutes the parietal cell acid pump, and pepsinogen (41 kDa) located in the chief cells. There was also a small but significant binding of antibodies to a preparation of Na,K-ATPase, an enzyme which is about 60% homologous to H,K-ATPase. Commercial preparations of hog gastric pepsinogen and pepsin bound pernicious anaemia IgG with equal efficacy. When sera from seven patients with the diagnosis pernicious anaemia were tested, all were found to contain auto-antibodies against H,K-ATPase as well as pepsinogen. In intact, isolated H,K-ATPase-containing vesicles the cytosolic part of the ATPase molecule is facing the outside of the vesicles. Both intact and trypsinized vesicles were incubated with patient sera and with a monoclonal antibody against H,K-ATPase. Pernicious anaemia IgG was found to bind to a cytosolic, trypsin-resistant structure, but the binding of the monoclonal antibody was lost upon trypsinization. The present results indicate that intracellular structures of the gastric mucosa, due to cell damage, may be exposed to immune-competent cells, which do not recognize these structures as 'self'.
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PMID:Characterization of antigenic structures in auto-immune atrophic gastritis with pernicious anaemia. The parietal cell H,K-ATPase and the chief cell pepsinogen are the two major antigens. 252 90


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