Determination of NMDA NR1 subunit copy number in recombinant NMDA receptors.
Co-expression of wild-type and mutated NMDA NR1 (N598R) subunits in Xenopus oocytes has been used to determine the stoichiometry of the NMDA receptor-channel. When expressed together, wild-type NR2A and mutant NR1 (N598R) subunits produced channels with a main conductance of 2.6 pS and a sublevel of 1.2 pS. These conductances were clearly different from those obtained from wild-type NR1 and wild-type NR2A channels which gave characteristic 50 pS events with a 40 pS sublevel. When wild-type and mutant NR1 subunits were co-expressed together with NR2A subunits a different channel type with a main conductance of 15.2 pS and a sublevel of 11.4 pS was obtained, as well as the 'all wild-type' and 'all mutant' channels described above. These results indicate that there are likely to be two copies of the NR1 subunit in each NMDA receptor complex.
Department of Pharmacology, University College London, U.K.
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Béhé
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Stern
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Wyllie
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Nassar
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Schoepfer
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Colquhoun
D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism*; D009154:Mutation; D017433:Protein Structure, Secondary; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; D018698:Glutamic Acid