Determination of NMDA NR1 subunit copy number in recombinant NMDA receptors

Proc Biol Sci. 1995 Nov 22;262(1364):205-13. doi: 10.1098/rspb.1995.0197.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Glutamic Acid / metabolism*
  • Mutation
  • Protein Structure, Secondary
  • Receptors, N-Methyl-D-Aspartate / genetics
  • Receptors, N-Methyl-D-Aspartate / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Xenopus


  • Receptors, N-Methyl-D-Aspartate
  • Recombinant Proteins
  • Glutamic Acid