Further evidence for excitatory amino acid transmission in the lateral habenular projection to the rostral raphe nuclei: Lesion-induced decrease of high affinity glutamate uptake

The intracellular glutamate concentration of oxygenated, isolated adult rat heart cells incubated with 0.15 mM glutamate amounts to 2.89 +/- 0.6 mM. Under these conditions the velocity of glutamate transport was 24.3 +/- 1.6 pmol.min-1.mg protein-1 and occurs via a high-affinity carrier characterized by an apparent affinity (K(m)) value of 0.18 +/- 0.03 mM. At high glutamate concentrations ( > 1mM) this high-affinity transport system is superimposed by additional uptake processes of a low affinity but a high capacity for glutamate. The 1.6-fold increased uptake of glutamate observed during 30 min of anoxic incubation of cardiomyocytes does not prevent an intracellular decrease in this amino acid to a concentration of 0.49 mM. After 15 min reoxygenation of cardiomyocytes the intracellular glutamate content increases to the control values of oxygenated cells. Only 2.4% of the glutamate increase after reoxygenation is due to the transport o glutamate from the incubation medium. The competitive inhibitor of transaminases, aminooxyacetate, prevents both the observed intracellular decrease in glutamate during anoxia and the increase in intracellular glutamate after reoxygenation of cardiomyocytes. Half of the amino groups needed for the synthesis of glutamate originate from intracellular alanine, which increases during anoxia and is metabolized during reoxygenation of cardiomyocytes. The velocity of the glutamate uptake of cardiomyocytes incubated in a medium containing 10 mM L-glutamate amounted to 728 +/- 140 pmol.min-1.mg protein-1. During anoxic incubation of cardiomyocytes at this high extracellular glutamate concentration, the intracellular glutamate breakdown may be compensated by a simultaneous uptake of this amino acid via the transport processes characterized by a high capacity

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Serotonergic cells of the rat raphe nuclei express mRNA of tyrosine kinase B (trkB), the high-affinity receptor for brain derived neurotrophic factor (BDNF)

Molecular Brain Research ◽

10.1016/s0169-328x(01)00183-8 ◽

2001 ◽

Vol 93 (1) ◽

pp. 56-63 ◽

Cited By ~ 51

Author(s):

T.R. Madhav ◽

Q. Pei ◽

T.S.C. Zetterström

Keyword(s):

Tyrosine Kinase ◽

Neurotrophic Factor ◽

Brain Derived Neurotrophic Factor ◽

Raphe Nuclei ◽

High Affinity ◽

High Affinity Receptor ◽

Affinity Receptor ◽

Raphé Nuclei

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Chemical activation of a high-affinity glutamate transporter in human erythrocytes and its implications for malaria-parasite–induced glutamate uptake

Blood ◽

10.1182/blood-2011-10-386003 ◽

2012 ◽

Vol 119 (15) ◽

pp. 3604-3612 ◽

Cited By ~ 14

Author(s):

Markus Winterberg ◽

Esther Rajendran ◽

Stefan Baumeister ◽

Sven Bietz ◽

Kiaran Kirk ◽

...

Keyword(s):

Malaria Parasite ◽

Excitatory Amino Acid ◽

Glutamate Uptake ◽

Chemical Activation ◽

Glutamate Transporter ◽

Human Erythrocytes ◽

Excitatory Amino Acid Transporter ◽

Western Blots ◽

High Affinity ◽

Parasite Plasmodium Falciparum

Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arsenite-induced L-glutamate influx was via a high-affinity, Na+-dependent system showing characteristics of members of the “excitatory amino acid transporter” (EAAT) family. Western blots and immunofluorescence assays revealed the presence of a member of this family, EAAT3, on the erythrocyte membrane. Erythrocytes infected with the malaria parasite Plasmodium falciparum take up glutamate from the extracellular environment. Although the majority of uptake is via a low-affinity Na+-independent pathway there is, in addition, a high-affinity uptake component, raising the possibility that the parasite activates the host cell glutamate transporter.

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A quantitative assessment of glutamate uptake into hippocampal synaptic terminals and astrocytes: New insights into a neuronal role for excitatory amino acid transporter 2 (EAAT2)

Neuroscience ◽

10.1016/j.neuroscience.2008.08.043 ◽

2008 ◽

Vol 157 (1) ◽

pp. 80-94 ◽

Cited By ~ 139

Author(s):

D.N. Furness ◽

Y. Dehnes ◽

A.Q. Akhtar ◽

D.J. Rossi ◽

M. Hamann ◽

...

Keyword(s):

Amino Acid ◽

Quantitative Assessment ◽

Excitatory Amino Acid ◽

Glutamate Uptake ◽

Amino Acid Transporter ◽

Excitatory Amino Acid Transporter ◽

Synaptic Terminals ◽

Acid Transporter

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Cryo-EM structures of excitatory amino acid transporter 3 visualize coupled substrate, sodium, and proton binding and transport

Science Advances ◽

10.1126/sciadv.abf5814 ◽

2021 ◽

Vol 7 (10) ◽

pp. eabf5814

Author(s):

Biao Qiu ◽

Doreen Matthies ◽

Eva Fortea ◽

Zhiheng Yu ◽

Olga Boudker

Keyword(s):

Amino Acid ◽

Excitatory Amino Acid ◽

Glutamate Uptake ◽

Amino Acid Transporter ◽

Sodium Ions ◽

Excitatory Amino Acid Transporter ◽

Proton Symport ◽

Functional States ◽

Rapid Transport ◽

Acid Transporter

Human excitatory amino acid transporter 3 (hEAAT3) mediates glutamate uptake in neurons, intestine, and kidney. Here, we report cryo-EM structures of hEAAT3 in several functional states where the transporter is empty, bound to coupled sodium ions only, or fully loaded with three sodium ions, a proton, and the substrate aspartate. The structures suggest that hEAAT3 operates by an elevator mechanism involving three functionally independent subunits. When the substrate-binding site is near the cytoplasm, it has a remarkably low affinity for the substrate, perhaps facilitating its release and allowing the rapid transport turnover. The mechanism of the coupled uptake of the sodium ions and the substrate is conserved across evolutionarily distant families and is augmented by coupling to protons in EAATs. The structures further suggest a mechanism by which a conserved glutamate residue mediates proton symport.

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