1. Molecular analysis of system N suggests novel physiological roles in nitrogen metabolism and synaptic transmission
- Author
-
Jon Storm-Mathisen, David R. Copenhagen, David Krizaj, Richard J. Reimer, Farrukh A. Chaudhry, Diane L. Barber, and Robert H. Edwards
- Subjects
Neurotransmitter transporter ,Nitrogen ,Intracellular pH ,Glutamine ,Molecular Sequence Data ,Glutamate-glutamine cycle ,Neurotransmission ,Biology ,Synaptic Transmission ,General Biochemistry, Genetics and Molecular Biology ,Glutamine transport ,Cell Line ,Animals ,Humans ,Amino Acid Sequence ,Cloning, Molecular ,chemistry.chemical_classification ,Neurotransmitter Agents ,Biochemistry, Genetics and Molecular Biology(all) ,Sodium ,Brain ,Membrane Proteins ,Membrane Transport Proteins ,Hydrogen-Ion Concentration ,Immunohistochemistry ,Cell biology ,Amino acid ,Rats ,Amino Acid Transport Systems, Neutral ,chemistry ,Biochemistry ,Organ Specificity ,Astrocytes ,Synapses ,Cotransporter ,Carrier Proteins ,Sequence Alignment - Abstract
The amino acid glutamine has a central role in nitrogen metabolism. Although the molecular mechanisms responsible for its transport across cell membranes remain poorly understood, classical amino acid transport system N appears particularly important. Using intracellular pH measurements, we have now identified an orphan protein related to a vesicular neurotransmitter transporter as system N. Functional analysis shows that this protein (SN1) involves H+ exchange as well as Na+ cotransport and, under physiological conditions, mediates glutamine efflux as well as uptake. Together with the pattern of SN1 expression, these unusual properties suggest novel physiological roles for system N in nitrogen metabolism and synaptic transmission.
- Published
- 2000