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Coupled and uncoupled proton movement by amino acid transport system N
Author(s) -
Chaudhry Farrukh A,
Krizaj David,
Larsson Peter,
Reimer Richard J,
Wreden Christopher,
StormMathisen Jon,
Copenhagen David,
Kavanaugh Michael,
Edwards Robert H
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.24.7041
Subject(s) - biology , glutamine , amino acid , biophysics , efflux , glutamate receptor , conductance , transporter , biochemistry , urea cycle , microbiology and biotechnology , arginine , physics , receptor , condensed matter physics , gene
The system N transporter SN1 has been proposed to mediate the efflux of glutamine from cells required to sustain the urea cycle and the glutamine–glutamate cycle that regenerates glutamate and γ‐aminobutyric acid (GABA) for synaptic release. We now show that SN1 also mediates an ionic conductance activated by glutamine, and this conductance is selective for H + . Although SN1 couples amino acid uptake to H + exchange, the glutamine‐gated H + conductance is not stoichiometrically coupled to transport. Protons thus permeate SN1 both coupled to and uncoupled from amino acid flux, providing novel mechanisms to regulate the transfer of glutamine between cells.