Mechanism of cation binding to the glutamate transporter EAAC1 probed with mutation of the conserved amino acid residue Thr101.

ABSTRACT: The glutamate transporter excitatory amino acid carrier 1 (EAAC1) catalyzes the co-transport of three Na(+) ions, one H(+) ion, and one glutamate molecule into the cell, in exchange for one K(+) ion. Na(+) binding to the glutamate-free form of the transporter generates a high affinity binding site for glutamate and is thus required for transport. Moreover, sodium binding to the transporters induces a basal anion conductance, which is further activated by glutamate. Here, we used the [Na(+)] dependence of this conductance as a read-out of Na(+) binding to the substrate-free transporter to study the impact of a highly conserved amino acid residue, Thr(101), in transmembrane domain 3. The apparent affinity of substrate-free EAAC1 for Na(+) was dramatically decreased by the T101A but not by th

SUBMITTER: Tao Z 

PROVIDER: S-EPMC2878536 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature