Macroscopic and Microscopic Properties of a Cloned Glutamate Transporter/Chloride Channel

The behavior of a Cl- channel associated with a glutamate transporter was studied using intracellular and patch recording techniques in Xenopus oocytes injected with human EAAT1 cRNA. Channels could be activated by application of glutamate to either face of excised membrane patches. The channel exhi...

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Published inThe Journal of neuroscience Vol. 18; no. 19; pp. 7650 - 7661
Main Authors Wadiche, Jacques I, Kavanaugh, Michael P
Format Journal Article
LanguageEnglish
Published United States Soc Neuroscience 01.10.1998
Society for Neuroscience
Subjects
Amino Acid Transport System X-AG
Animals
Anions - pharmacokinetics
Aspartic Acid - pharmacology
ATP-Binding Cassette Transporters - genetics
ATP-Binding Cassette Transporters - metabolism
Biological Transport - genetics
Brain Chemistry - physiology
Chloride Channels - genetics
Chloride Channels - metabolism
Cloning, Molecular
Electric Conductivity
Glutamic Acid - pharmacokinetics
Humans
Ion Channel Gating - physiology
Kinetics
Membrane Potentials - physiology
Oocytes - physiology
Patch-Clamp Techniques
Potassium - pharmacokinetics
Protons
Sodium - pharmacokinetics
Xenopus
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Summary:The behavior of a Cl- channel associated with a glutamate transporter was studied using intracellular and patch recording techniques in Xenopus oocytes injected with human EAAT1 cRNA. Channels could be activated by application of glutamate to either face of excised membrane patches. The channel exhibited strong selectivity for amphipathic anions and had a minimum pore diameter of approximately 5A. Glutamate flux exhibited a much greater temperature dependence than Cl- flux. Stationary and nonstationary noise analysis was consistent with a sub-femtosiemen Cl- conductance and a maximum channel Po << 1. The glutamate binding rate was similar to estimates for receptor binding. After glutamate binding, channels activated rapidly followed by a relaxation phase. Differences in the macroscopic kinetics of channels activated by concentration jumps of L-glutamate or D-aspartate were correlated with differences in uptake kinetics, indicating a close correspondence of channel gating to state transitions in the transporter cycle.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0270-6474
1529-2401
DOI:10.1523/jneurosci.18-19-07650.1998