ATP‐binding properties of P glycoprotein from multidrug‐resistant KB cells

Abstract
The photoaffinity reagent 8-azido-α-[32P]ATP was used to label a protein of 170 kDa in membrane vesicle preparations from a highly multidrug-resistant cell line, KB-V1, but not from the drug-sensitive parental cell line KB-3-1. The 170-kDa labeled protein was immunoprecipitated with a monoclonal antibody (MRK-16) to P glycoprotein. Both ATP and GTP inhibited labeling by 8-azido-α-[52P]ATP. Labeling of P170 was not inhibited by 5 mM ADP, 5 mm ribose-5-phosphate, or 100 μm vinblastine. These data directly demonstrate that P glycoprotein has a nucleotide-binding site that could supply energy for drug transport.— Cornwell, M. M.; Tsuruo, T; Gottesman, M. M.; Pastan, I. ATP-binding properties of P glycoprotein from multidrug-resistant KB cells. FASEB J 1: 51-54; 1987.