Competitive intra- and extracellular nutrient sensing by transporter homologue
Journal article, 2005

Recent studies of Saccharomyces cerevisiae revealed sensors that detect extracellular amino acids (Ssy1p) or glucose (Snf3p and Rgt2p) and are evolutionarily related to the transporters of these nutrients. An intriguing question is whether the evolutionary transformation of transporters into nontransporting sensors reflects a homeostatic capability of transporter-like sensors that could not be easily attained by other types of sensors. We previously found SSY1 mutants with an increased basal level of signaling and increased apparent affinity to sensed extracellular amino acids. On this basis, we propose and test a general model for transporter-like sensors in which occupation of a single, central ligand binding site increases the activation energy needed for the conformational shift between an outward-facing, signaling conformation and an inward-facing, nonsignaling conformation. As predicted, intracellular leucine accumulation competitively inhibits sensing of extracellular amino acids. Thus, a single sensor allows the cell to respond to changes in nutrient availability through detection of the relative concentrations of intra- and extracellular ligand.

Nutrient sensing

amino acid sensing


carrier transport


Boqian Wu

Carlsberg Research Center

Kim Ottow

Technical University of Denmark (DTU)

Carlsberg Research Center

Peter Poulsen

Carlsberg Research Center

University of Copenhagen

Richard F Gaber

Northwestern University

Carlsberg Research Center

Eva Albers

Chalmers, Chemical and Biological Engineering, Molecular Biotechnology

Morten C Kielland-Brandt

Carlsberg Research Center

Journal of Cell Biology

0021-9525 (ISSN)

Vol. 173 3 327-331

Subject Categories

Biochemistry and Molecular Biology



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