Functional significance of N- and C-terminus of the amino acid transporters EAAC1 and ASCT1: characterization of chimeric transporters.
To localize functionally significant domains in the amino acid transporters of mouse brain mEAAC1 and mASCT1, cRNA encoding for wild-type and chimeric transporters was injected into Xenopus oocytes. Activity of expressed transporters was investigated by measurements of uptake of 3H-labeled glutamate and serine and of glutamate- and serine-induced currents under voltage clamp. Though all transporters accept glutamate and serine as substrate, the central part of the protein (Ala94-Met418 of mEAAC1 and Ala119-Ile393 of mASCT1) determines substrate selectivity. The C-terminus rectifies the interaction with the respective substrate. A channel mode of the glutamate transporter can be activated by glutamate and serine, and the N- and C-termini of the mEAAC1 seem to be essential for the channel formation.
Li
J
J
Max-Planck-Institute for Biophysics, Frankfurt/Main, Germany.
Fei
J
J
Huang
F
F
Guo
L H
LH
Schwarz
W
W
D000595:Amino Acid Sequence; D027322:Amino Acid Transport System X-AG; D026905:Amino Acid Transport Systems; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D050580:Excitatory Amino Acid Transporter 3; D005260:Female; D050491:Glutamate Plasma Membrane Transport Proteins; D018698:Glutamic Acid / Q000378:metabolism; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D027981:Symporters; D014982:Xenopus laevis
D027322:Amino Acid Transport System X-AG; D026905:Amino Acid Transport Systems; D000596:Amino Acids; D002352:Carrier Proteins; D017931:DNA Primers; D050580:Excitatory Amino Acid Transporter 3; D050491:Glutamate Plasma Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C493399:Slc1a1 protein, mouse; D027981:Symporters; D018698:Glutamic Acid; D012694:Serine