THE GS-X PUMP IN PLANT, YEAST, AND ANIMAL-CELLS - STRUCTURE, FUNCTION, AND GENE-EXPRESSION

This review addresses the recent molecular identification of several m embers of the glutathione S-conjugate (GS-X) pump family, a new class of ATP-binding cassette (ABC) transporters responsible for the elimina tion and/or sequestration of pharmacologically and agronomically impor tant compounds in mammalian, yeast and plant cells. The molecular stru cture and function of GS-X pumps encoded by MRP, cMOAT, YCF1, and AtMR P genes, have been conserved throughout molecular evolution. The physi ologic function of GS-X pumps is closely related with cellular detoxif ication, oxidative stress, inflammation, and cancer drug resistance. C oordinated expression of GS-X pump genes, e.g., MRP1 and YCF1, and gam ma-glutamylcystaine synthetase, a rate-limiting enzyme of cellular glu tathione (GSH) biosynthesis, has been frequently observed.