Abolition of substrate-dependent currents by tyrosine mutation in the transmembrane domain of glutamate transporter.
By site-directed mutagenesis we examined the roles of tyrosine residues (Tyr127) in the putative transmembrane domain of rat glutamate transporter (GLAST). When expressed in Xenopus oocytes, Y127F mutant protein, which was localized in plasma membranes of oocytes, completely abolished glutamate uptake currents but did not affect the intrinsic substrate-independent currents. Coexpression of wild type and mutant transporters supports that the Y127F mutation did not elicit glutamate efflux. The efflux of glutamate by wild type or Y127F mutant transporters was measured under the condition of ion perturbation where transporters run in the reverse direction.
Choi
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Developmental Biology Program, University of Wisconsin, Madison 53706, USA.
Chiu
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D027322:Amino Acid Transport System X-AG; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004553:Electric Conductivity; D004594:Electrophysiology; D018698:Glutamic Acid / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009865:Oocytes; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics*; D014981:Xenopus
D027322:Amino Acid Transport System X-AG; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D018698:Glutamic Acid; D014443:Tyrosine