P-glycoprotein transports corticosterone and is photoaffinity-labeled by the steroid.
Multi-drug-resistant cells overproduce a 130-180-kDa integral membrane phosphoglycoprotein known as P-glycoprotein which acts as an energy-dependent drug efflux pump. While P-glycoprotein has been shown to transport hydrophobic anti-tumor drugs out of multi-drug-resistant cells in tissue culture, its endogenous substrates remain unknown. This report shows that 3H-corticosterone can specifically photoaffinity label P-glycoprotein. Furthermore, corticosterone is effluxed from multi-drug-resistant cells by P-glycoprotein. These data suggest that corticosterone may be an endogenous substrate for P-glycoprotein.
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461.
D C
DC
Wolf
S B
SB
Horwitz
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000302:Adrenal Cortex / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002417:Cattle; D003345:Corticosterone / Q000378:metabolism*; D004351:Drug Resistance; D005089:Exocytosis; D066298:In Vitro Techniques; D008562:Membrane Glycoproteins / Q000378:metabolism*; D014316:Tritium
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000345:Affinity Labels; D008562:Membrane Glycoproteins; D014316:Tritium; D003345:Corticosterone