Expression of the mammalian system A neutral amino acid transporter in Xenopus oocytes.

Journal Article (Journal Article)

In this report, we demonstrate the expression of the mammalian System A neutral amino acid transporter in Xenopus laevis oocytes following microinjection of mRNA from rat liver, Chinese hamster ovary (CHO) cells, and human placenta. Stage 6 oocytes were injected with poly(A+) mRNA from one of these three sources and incubated for 24 h prior to assaying Na(+)-dependent 2-aminoisobutyric acid transport to monitor the increase in System A activity. The endogenous 2-aminoisobutyric acid uptake rates in oocytes were sufficiently slow so as to provide a low background value that was subtracted to obtain transport rates for the mammalian carrier alone. The degree of expression of the mammalian System A activity in Xenopus oocytes corresponded to the known transport rates in the tissue from which the mRNA was prepared. For example, hepatic mRNA from glucagon-treated rats produced greater System A activity than mRNA from control animals, and the mRNA from the CHO transport mutant cell line alar4-H3.9, which overproduces System A, resulted in higher transport rates than mRNA from the parental cell line (CHO-K1). Fractionation of total mRNA poly(A+) by nondenaturing agarose gel electrophoresis revealed transport activity associated with a 2.0-2.5-kilobase mRNA fraction common to each of the three tissues tested.

Full Text

Duke Authors

Cited Authors

  • Tarnuzzer, RW; Campa, MJ; Qian, NX; Englesberg, E; Kilberg, MS

Published Date

  • August 15, 1990

Published In

Volume / Issue

  • 265 / 23

Start / End Page

  • 13914 - 13917

PubMed ID

  • 2380194

International Standard Serial Number (ISSN)

  • 0021-9258


  • eng

Conference Location

  • United States