Conformationally Sensitive Reactivity to Permeant Sulfhydryl Reagents of Cysteine Residues Engineered into Helical Hairpin 1 of the Glutamate Transporter GLT-1

2007 ◽  
Vol 71 (5) ◽  
pp. 1341-1348 ◽  
Author(s):  
Irina Shlaifer ◽  
Baruch I. Kanner
Keyword(s):  
Glutamate Transporter ◽  
Cysteine Residues ◽  
Sulfhydryl Reagents ◽  
Helical Hairpin

Mercuric chloride uncouples glutamate uptake from the countertransport of hydroxyl equivalents

1996 ◽  
Vol 271 (5) ◽  
pp. C1487-C1493 ◽  
Author(s):  
T. N. Nagaraja ◽  
N. Brookes
Keyword(s):  
Ph Regulation ◽  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Glutamate Transport ◽  
Inhibitor Concentration ◽  
Intracellular Acidification ◽  
Sulfhydryl Reagents ◽  
Hydroxyl Ion ◽  
Order Of Magnitude ◽  
Mercuric Mercury

The cotransport of sodium and glutamate by system X(AG)- is believed to be coupled to the countertransport of potassium and hydroxyl ion equivalents. Accordingly, the uptake of glutamate or D-aspartate in astrocytes is accompanied by an intracellular acidification. Here, we report that HgCl2 blocks the glutamate-induced acidification with an approximate 50% inhibitor concentration (IC50) of 55 nM, an order of magnitude below its IC50 for inhibition of glutamate uptake. At 100 nM HgCl2, glutamate-induced acidification was abolished, whereas glutamate uptake was unaffected. D-Aspartate-induced acidification was equally sensitive to HgCl2, indicating that HgCl2 blocked a transporter-mediated, rather than a receptor-mediated, acidification. Unaltered responses to acute acid and alkaline loads showed that HgCl2 was not acting indirectly via a change in pH regulation. We conclude that HgCl2 acted directly on the glutamate transporter to uncouple the uptake of glutamate from the export of hydroxyl equivalents. In contrast, two other sulfhydryl reagents, p-chloromercuribenzensulfonate and N-ethylmaleimide, failed to discriminate between glutamate-induced acidification and glutamate uptake. An additional effect of > or = 100 nM HgCl2, in this case shared by p-chlormercuribenzenesulfonate, was transient intracellular acidification. There is evidence that glutamate transport is regulated by intracellular pH. Mercuric mercury may disrupt the regulation of glutamate transport at lower concentrations than those that block transport.

Antisense knockdown of the glial glutamate transporter GLT-1 exacerbates hippocampal neuronal damage following traumatic injury to rat brain

2001 ◽  
Vol 13 (1) ◽  
pp. 119-128 ◽  
Author(s):  
Vemuganti L. Raghavendra Rao ◽  
Aclan Dogan ◽  
Kellie K. Bowen ◽  
Kathryn G. Todd ◽  
Robert J. Dempsey
Keyword(s):  
Rat Brain ◽  
Neuronal Damage ◽  
Traumatic Injury ◽  
Glutamate Transporter ◽  
Glial Glutamate Transporter ◽  
Antisense Knockdown
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