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Neuron. 1998 Sep;21(3):623-32.

Biotinylation of single cysteine mutants of the glutamate transporter GLT-1 from rat brain reveals its unusual topology.

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1
Department of Biochemistry, Hadassah Medical School, The Hebrew University, Jerusalem, Israel.

Abstract

In the central nervous system, (Na+ + K+)-coupled glutamate transporters restrict the neurotoxicity of this transmitter and limit the duration of synaptic excitation at some synapses. The various isotransporters exhibit a particularly high homology in an extended hydrophobic domain of ill-defined topology that contains several determinants involved in ion and transmitter binding. Here, we describe the determination of the membrane topology of the cloned astroglial glutamate transporter GLT-1. A series of functional transporters containing single cysteines was engineered. Their topological disposition was determined by using a biotinylated sulfhydryl reagent. The glutamate transporter has eight transmembrane domains long enough to span the membrane as et heiices. Strikingly, between the seventh and eighth domains, a structure reminiscent of a pore loop and an outward-facing hydrophobic linker are positioned.

PMID:
9768848
[Indexed for MEDLINE]
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