Further characterization of the human adrenal-derived P-glycoprotein recognized by monoclonal antibody MRK 16 reacting with only human P-glycoprotein.

This paper describes further characterization of the 170-180-kDa glycoprotein (P-glycoprotein) recognized by the monoclonal antibody MRK 16 in the human adrenal. By electron microscopy, P-glycoprotein was observed in the adrenal cell membranes. However, MRK 16-defined P-glycoprotein was not found in cow, pig, horse, monkey or rabbit adrenal, indicating that MRK 16 recognizes the non-homologous part of P-glycoprotein of various species. Eleven out of 16 adrenal tumors including 4 cases of primary aldosteronism and 7 cases of Cushing syndrome were intensely stained with MRK 16, whereas pheochromocytoma, non-functioning adrenocortical adenoma with no associated increase of serum adrenal-derived hormones and myolipoma of the adrenal were not. Finally, P-glycoprotein-MRK 16-protein A-Sepharose complex derived from human adrenal possessed marked ATPase activity. Taken together, these data suggest that P-glycoprotein may play a physiological role in the human adrenal.

adriamycin‐resistant K562

monoclonal antibody

sodium dodecyl sulfate poly aery lamide gel electropho‐resis

periodate‐lysine‐paraformaldehyde

kilo‐daltons

3‐[(3‐cholamidopropyl)dimethylammonio]‐1‐propane sulfonate

avidin‐biotin‐peroxidase complex