Ruetz S, Brault M, Kast C, Hemenway C, Heitman J, Grant C E, Cole S P, Deeley R G, Gros P
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
J Biol Chem. 1996 Feb 23;271(8):4154-60. doi: 10.1074/jbc.271.8.4154.
The multidrug resistance-associated protein (MRP) is a member of the ATP binding cassette superfamily of transporters which includes the mammalian P-glycoproteins (P-gp) family. In order to facilitate the biochemical and genetic analyses of MRP, we have expressed human MRP in the yeast Saccharomyces cerevisiae and have compared its functional properties to those of the mouse Mdr3 P-gp isoform. Expression of both MRP and Mdr3 in the anthracycline hypersensitive mutant VASY2563 restored cellular resistance to Adriamycin in this mutant. MRP and Mdr3 expression produced pleiotropic effects on drug resistance in this mutant, as corresponding VASY2563 transformants also acquired resistance to the anti-fungal agent FK506 and to the K+/H+ ionophore valinomycin. The appearance of increased cellular resistance to the toxic effect of Adriamycin (ADM) in MRP and Mdr3 transformants was concomitant with a reduced intracellular accumulation of [14C]ADM in spheroplasts prepared from these cells. Moreover, MRP and Mdr3, but not control spheroplasts, could mediate a time-dependent reduction in the overall cell-associated [14C]ADM from preloaded cells, suggesting the presence of an active ADM transport mechanism in MRP and Mdr3 transformants. Finally, human MRP was found to complement the biological activity of the yeast peptide pheromone transporter Ste6 and partially restored mating in a sterile ste6 null mutant. These findings suggest that despite their relatively low level of structural homology, MRP and P-gp share similar functional aspects, since both proteins can mediate transport of chemotherapeutic drugs and the a mating peptide pheromone in yeast.
多药耐药相关蛋白（MRP）是ATP结合盒转运体超家族的成员，该家族包括哺乳动物P-糖蛋白（P-gp）家族。为了便于对MRP进行生化和遗传分析，我们已在酿酒酵母中表达了人MRP，并将其功能特性与小鼠Mdr3 P-gp同工型的功能特性进行了比较。MRP和Mdr3在阿霉素超敏突变体VASY2563中的表达恢复了该突变体细胞对阿霉素的抗性。MRP和Mdr3的表达对该突变体的耐药性产生了多效性影响，因为相应的VASY2563转化体也获得了对抗真菌剂FK506和K+/H+离子载体缬氨霉素的抗性。MRP和Mdr3转化体中细胞对阿霉素（ADM）毒性作用的抗性增加，同时这些细胞制备的原生质体中[14C]ADM的细胞内积累减少。此外，MRP和Mdr3，而不是对照原生质体，可以介导预加载细胞中与细胞相关的总[14C]ADM随时间的减少，这表明MRP和Mdr3转化体中存在活跃的ADM转运机制。最后，发现人MRP可补充酵母肽信息素转运体Ste6的生物学活性，并在无菌的ste6缺失突变体中部分恢复交配。这些发现表明，尽管MRP和P-gp的结构同源性相对较低，但它们具有相似的功能方面，因为这两种蛋白都可以介导化疗药物和酵母中的α交配肽信息素的转运。
