P Glycoproteins

A subfamily of transmembrane Proteins from the superfamily of ATP-Binding Cassette Transporters that are closely related in sequence to P-Glycoprotein. When overexpressed, they function as ATP-dependent efflux pumps able to extrude lipophilic Drugs, especially Antineoplastic Agents, from Cells causing Multidrug Resistance (Drug Resistance, Multiple). Although P-Glycoproteins share functional similarities to Multidrug Resistance-Associated Proteins they are two distinct subclasses of ATP-Binding Cassette Transporters, and have little Sequence Homology.