Mutation of an amino acid residue influencing potassium coupling in the glutamate transporter GLT-1 induces obligate exchange.
J Biol Chem
; 272(3): 1703-8, 1997 Jan 17.
Article
em En
| MEDLINE
| ID: mdl-8999849
ABSTRACT
Glutamate transporters maintain low synaptic concentrations of neurotransmitter by coupling uptake to flux of other ions. After cotransport of glutamic acid with Na+, the cycle is completed by countertransport of K+. We have identified an amino acid residue (glutamate 404) influencing ion coupling in a domain of the transporter implicated previously in kainate binding. Mutation of this residue to aspartate (E404D) prevents both forward and reverse transport induced by K+. Sodium-dependent transmitter exchange and a transporter-mediated chloride conductance are unaffected by the mutation, indicating that this residue selectively influences potassium flux coupling. The results support a kinetic model in which sodium and potassium are translocated in distinct steps and suggest that this highly conserved region of the transporter is intimately associated with the ion permeation pathway.
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Base de dados:
MEDLINE
Assunto principal:
Potássio
/
Transportadores de Cassetes de Ligação de ATP
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article