Neuronal and glial glycine transporters have different stoichiometries

Neuron. 2000 Feb;25(2):373-83. doi: 10.1016/s0896-6273(00)80901-0.


A neurotransmitter transporter can potentially mediate uptake or release of substrate, and its stoichiometry is a key factor that controls the driving force and thus the neurotransmitter flux direction. We have used a combination of electrophysiology and radio-tracing techniques to evaluate the stoichiometries of two glycine transporters involved in glycinergic or glutamatergic transmission. We show that GlyT2a, a transporter present in glycinergic boutons, has a stoichiometry of 3 Na+/Cl-/glycine, which predicts effective glycine accumulation in all physiological conditions. GlyT1b, a glial transporter, has a stoichiometry of 2 Na+/Cl-/ glycine, which predicts that glycine can be exported or imported, depending on physiological conditions. GlyT1b may thus modulate glutamatergic synapses by increasing or decreasing the glycine concentration around N-methyl-D-aspartate receptors (NMDARs).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport Systems, Neutral*
  • Animals
  • Biological Transport / physiology
  • Carrier Proteins / analysis*
  • Carrier Proteins / metabolism
  • Electric Conductivity
  • Electrophysiology
  • Extracellular Space / metabolism
  • Glycine / pharmacokinetics
  • Glycine Plasma Membrane Transport Proteins
  • Kinetics
  • Membrane Potentials / physiology
  • Neuroglia / chemistry*
  • Neuroglia / metabolism
  • Neurons / chemistry*
  • Neurons / metabolism
  • Oocytes / physiology
  • Rats
  • Sodium / pharmacokinetics
  • Xenopus laevis


  • Amino Acid Transport Systems, Neutral
  • Carrier Proteins
  • Glycine Plasma Membrane Transport Proteins
  • Sodium
  • Glycine