title: Cellular localization of the multidrug-resistance gene product P-glycoprotein in normal human tissues.
abstract: Monoclonal antibody MRK16 was used to determine the location of P-glycoprotein, the product of the multidrug-resistance gene (MDR1), in normal human tissues. The protein was found to be concentrated in a small number of specific sites. Most tissues examined revealed very little P-glycoprotein. However, certain cell types in liver, pancreas, kidney, colon, and jejunum showed specific localization of P-glycoprotein. In liver, P-glycoprotein was found exclusively on the biliary canalicular front of hepatocytes and on the apical surface of epithelial cells in small biliary ductules. In pancreas, P-glycoprotein was found on the apical surface of the epithelial cells of small ductules but not larger pancreatic ducts. In kidney, P-glycoprotein was found concentrated on the apical surface of epithelial cells of the proximal tubules. Colon and jejunum both showed high levels of P-glycoprotein on the apical surfaces of superficial columnar epithelial cells. Adrenal gland showed high levels of P-glycoprotein diffusely distributed on the surface of cells in both the cortex and medulla. These results suggest that the protein has a role in the normal secretion of metabolites and certain anti-cancer drugs into bile, urine, and directly into the lumen of the gastrointestinal tract.
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D004351:Drug Resistance; D000939:Epitopes / Q000032:analysis; D005796:Genes; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis / Q000235:genetics*; D009928:Organ Specificity
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D000939:Epitopes; D008562:Membrane Glycoproteins