The alpha 1-adrenergic photoaffinity probe [125I]arylazidoprazosin binds to a specific peptide of P-glycoprotein in multidrug-resistant cells.
Much evidence suggests that P-glycoprotein (P-gp) confers multidrug-resistance (MDR) in tumor cells by energy-dependent efflux of hydrophobic cytotoxic agents. In this study, we have used the alpha 1-adrenergic photoaffinity probe, [125I]arylazidoprazosin ([125I]AAP), and identified P-gp as a specific acceptor for prazosin. Drugs to which MDR cells are resistant, including vincristine, vinblastine, doxorubicin, actinomycin D and colchicine as well as agents reversing MDR, including verapamil, nicardipine, prenylamine, diltiazem, trifluoperazine, dibucaine, reserpine, monensin, and progesterone, differentially reduced [125I]AAP photolabeling of P-gp. We also analyzed the influence of alpha 2-adrenergic drugs and dopaminergic drugs on [125I]AAP photolabeling of P-gp. Limited proteolysis of [125I]AAP photolabeled P-gp with Staphylococcus aureus V8 protease revealed that prazosin binds to a single 8 kDa fragment of P-gp.
Safa
A R
AR
Department of Medicine, University of Chicago, Pritzker School of Medicine, IL 60637.
Agresti
M
M
Tamai
I
I
Mehta
N D
ND
Vahabi
S
S
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000378:metabolism*; D002460:Cell Line; D003078:Colchicine / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D003609:Dactinomycin / Q000494:pharmacology; D004351:Drug Resistance / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D007457:Iodine Radioisotopes; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D010449:Peptide Mapping; D011224:Prazosin / Q000031:analogs & derivatives; D011799:Quinazolines / Q000378:metabolism*; D014748:Vinca Alkaloids / Q000494:pharmacology*; D014750:Vincristine / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000345:Affinity Labels; D001386:Azides; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D011799:Quinazolines; D014748:Vinca Alkaloids; D003609:Dactinomycin; D014750:Vincristine; C041552:azidoprazosin; D003078:Colchicine; D011224:Prazosin