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Updated: Apr 20, 2026

Deriving the Time Course of Glutamate Clearance with a Deconvolution Analysis of Astrocytic Transporter Currents
Published on: August 7, 2013
Vesicular glutamate transporters use flexible anion and cation binding sites for efficient accumulation of
Julia Preobraschenski1, Johannes-Friedrich Zander2, Toshiharu Suzuki3
1Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Abstract:
Vesicular glutamate transporters (VGLUTs) accumulate the neurotransmitter glutamate in synaptic vesicles. Transport depends on a V-ATPase-dependent electrochemical proton gradient (ΔμH+) and requires chloride ions, but how chloride acts and how ionic and charge balance is maintained during transport is controversial. Using a reconstitution approach, we used an exogenous proton pump to drive VGLUT-mediated transport either in liposomes containing purified VGLUT1 or in synaptic vesicles fused with proton-pump-containing liposomes. Our data show that chloride stimulation can be induced at both sides of the membrane. Moreover, chloride competes with glutamate at high concentrations. In addition, VGLUT1 possesses a cation binding site capable of binding H+ or K+ ions, allowing for proton antiport or K+ / H+ exchange. We conclude that VGLUTs contain two anion binding sites and one cation binding site, allowing the transporter to adjust to the changing ionic conditions during vesicle filling without being dependent on other transporters or channels.
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