Picture of a sphere with binary code

Making Strathclyde research discoverable to the world...

The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs. It exposes Strathclyde's world leading Open Access research to many of the world's leading resource discovery tools, and from there onto the screens of researchers around the world.

Explore Strathclyde Open Access research content

Functional and molecular characteristics of system L in human breast cells

Shennan, David B. and Thomson, Jean and Barber, M.C. and Travers, M. (2003) Functional and molecular characteristics of system L in human breast cells. BBA - Biomembranes, 1611 (1-2). pp. 81-90. ISSN 0005-2736

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

The functional and molecular properties of system in human mammary cancer cells (MDA-MB-231 and MCF-7) have been examined. All transport experiments were conducted under Na+-free conditions. α-Aminoisobutyric acid (AIB) uptake by MDA-MB-231 and MCF-7 cells was almost abolished by BCH (2-amino-2-norbornane-carboxylic acid). AIB uptake by MDA-MB-231 cells was also inhibited by -alanine (83.6%), -lysine (75.6%) but not by -proline. Similarly, -lysine and -alanine, respectively, reduced AIB influx into MCF-7 cells by 45.3% and 63.7%. The Km of AIB uptake into MDA-MB-231 and MCF-7 cells was, respectively, 1.6 and 8.8 mM, whereas the Vmax was, respectively, 9.7 and 110.0 nmol/mg protein/10 min. AIB efflux from MDA-MB-231 and MCF-7 cells was trans-stimulated by BCH, -glutamine, -alanine, -leucine, -lysine and AIB (all at 2 mM). In contrast, -glutamate, -proline, -arginine and MeAIB had no effect. The interaction between -lysine and AIB efflux was one of low affinity. The fractional release of AIB from MDA-MB-231 cells was trans-accelerated by -leucine and -tryptophan but not by -alanine. MDA-MB-231 and MCF-7 cells expressed LAT1 and CD98 mRNA. MCF-7 cells also expressed LAT2 mRNA. The results suggest that AIB transport in mammary cancer cells under Na+-free conditions is predominantly via system which acts as an exchange mechanism. The differences in the kinetics of AIB transport between MDA-MB-231 and MCF-7 cells may be due to the differential expression of LAT2.