Send to

Choose Destination
Cell. 1999 Dec 23;99(7):769-80.

Molecular analysis of system N suggests novel physiological roles in nitrogen metabolism and synaptic transmission.

Author information

Department of Neurology, UCSF School of Medicine, San Francisco, California 94143-0435, USA.


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.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center