EXPRESSION OF THE MOUSE MACROPHAGE CYSTINE TRANSPORTER IN XENOPUS-LAEVIS OOCYTES

System xc- mediates transport of cystine and glutamate across the mammalian plasma membrane in a Na+-independent manner. This transport activity can be induced in mouse peritoneal macrophages during culture by diethylmaleate, a sulfhydryl-reactive agent. We injected mRNA from such macrophages into Xenopus oocytes and demonstrated the expression of System xc-, i.e., a Na+-independent, glutamate-inhibitable cystine transport system. The expressed cystine transport activity depended on the assay temperature, in that cystine uptake measured at 37 °C was severalfold higher than that measured at 20 °C. Injection of size-fractionated mRNA indicated that the System xc- transporter of the mouse macrophage is encoded by mRNA of 1.5 to 2.9 kb. © 1991.