NMDA receptor channels: subunit-specific potentiation by reducing agents.
Sulfhydryl redox agents affect NMDA receptor activity. We investigated a putative redox site in four recombinant NMDA receptors. In 293 cells expressing NR1-NR2A channels dithiothreitol (DTT) rapidly potentiated L-glutamate-activated whole-cell currents and decreased the time course of desensitization and deactivation. Part of the current potentiation (reversible component) and all kinetic changes reversed upon washout. The remaining potentiation (persistent component) was abolished by an oxidizing agent. The N-terminal 370 residues of NR2A mediate the reversible component in chimeric NR2 subunits. In cells expressing the NR1-NR2B, -NR2C, and -NR2D channels DTT elicited only a slowly developing, persistent potentiation and increased the deactivation time course. In these, but not in NR1-NR2A, the DTT effect was rendered insensitive to reoxidation by alkylation. Reduced glutathione mimicked the DTT effects only in the NR1-NR2A receptor. Hence, molecularly distinct NMDA receptors differ profoundly in their responses to sulfhydryl redox agents.
Köhr
G
G
Center for Molecular Biology (ZMBH), University of Heidelberg, Federal Republic of Germany.
Eckardt
S
S
Lüddens
H
H
Monyer
H
H
Seeburg
P H
PH
D000409:Alanine; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003545:Cysteine; D004229:Dithiothreitol / Q000494:pharmacology*; D004357:Drug Synergism; D005033:Ethylmaleimide / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D005978:Glutathione / Q000494:pharmacology*; D006801:Humans; D007473:Ion Channels / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D007668:Kidney; D007700:Kinetics; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D012694:Serine; D014162:Transfection
D005971:Glutamates; D007473:Ion Channels; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D016194:Receptors, N-Methyl-D-Aspartate; D011993:Recombinant Fusion Proteins; D018698:Glutamic Acid; D012694:Serine; D005978:Glutathione; D003545:Cysteine; D005033:Ethylmaleimide; D000409:Alanine; D004229:Dithiothreitol