title: Colocalization of the apical Cl-/HCO3- exchanger PAT1 and gastric H-K-ATPase in stomach parietal cells.
abstract: The apical Cl-/HCO exchanger called the putative anion transporter (PAT1; SLC26A6) is expressed on apical membranes of villus cells in the duodenum, but its location in the stomach remains unknown. Here we examined the cell distribution and membrane location of PAT1 in mouse stomach. Immunofluorescence labeling studies with anti-PAT1 antibodies and Dolichos biflorus agglutinin indicated the exclusive expression of PAT1 in gastric parietal cells. Double immunocytochemical staining revealed colocalization of PAT1 with the gastric H-K-ATPase, consistent with expression in tubulovesicles and/or the secretory canaliculus. Radiolabeled 36Cl flux studies demonstrated the functional presence of Cl-/HCO exchange in purified tubulovesicles of parietal cells. The expression of PAT1 was significantly decreased in parietal cells of gastric H-K-ATPase-null mice, which exhibit a sharp reduction in tubulovesicle membranes. These data indicate that the Cl-/HCO exchanger PAT1 is localized on tubulovesicular membranes, and they are consistent with the hypothesis that it functions in the maintenance of intravesicular ion concentrations in the resting state and dehydration of vesicles derived from the secretory membranes following the transition from the stimulated to the resting state.
authors.affiliation: Department of Medicine, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, Ohio 45267-0585, USA.
authors.forename: Snezana
authors.initials: S
authors.lastname: Petrovic
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
authors.forename: Liyun
authors.initials: L
authors.lastname: Ma
authors.forename: Ursula
authors.initials: U
authors.lastname: Seidler
authors.forename: John G
authors.initials: JG
authors.lastname: Forte
authors.forename: Gary E
authors.initials: GE
authors.lastname: Shull
authors.forename: Manoocher
authors.initials: M
authors.lastname: Soleimani
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism; D004064:Digestive System / Q000378:metabolism; D017506:H(+)-K(+)-Exchanging ATPase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics; D010295:Parietal Cells, Gastric / Q000378:metabolism*; D037121:Plant Lectins; D011817:Rabbits; D013194:Staining and Labeling; D013270:Stomach / Q000201:enzymology*; D000076988:Sulfate Transporters; D014018:Tissue Distribution
chemical_list: D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D037121:Plant Lectins; C439529:SLC26A6 protein, human; D000076988:Sulfate Transporters; C036554:dolichos biflorus agglutinin; D017506:H(+)-K(+)-Exchanging ATPase