EXPRESSION AND CHARACTERIZATION OF THE MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN IN INSECT CELLS INFECTED WITH A RECOMBINANT BACULOVIRUS

The protein encoded by the multidrug resistance-associated protein (MR P) gene was examined after infection of SF21 insect cells with recombi nant baculovirus containing a full-length MRP cDNA. The time course of appearance of the protein as determined by western blot analysis reve aled that maximum levels occurred 2 days postinfection. The amount of MRP made in this system was somewhat variable, but levels that were ab out 4-fold greater than that found in HL60/ADR cells could be achieved . The protein appeared to be full-length but was present in a highly d eglycosylated form. The P170 (MRP) was phosphorylated and located excl usively in membranes of infected cells. P170 (MRP) synthesized in this system was capable of carrying out the ATP-dependent transport of leu kotriene C-4 into isolated membrane vesicles. The results thus indicat e that MRP synthesized in insect cells is functional and has propertie s similar to the authentic protein found overexpressed in certain mult idrug-resistant isolates. Copyright (C) 1996 Elsevier Science Inc.