title: Coexpression of postsynaptic density-95 protein with NMDA receptors results in enhanced receptor expression together with a decreased sensitivity to L-glutamate.
abstract: Coexpression in human embryonic kidney (HEK) 293 cells of the postsynaptic density-95 protein (PSD-95) with NMDA receptor NR2A or NR2B single subunits or NR1-1a/NR2A and NR1-1a/NR2B subunit combinations induced an approximately threefold increase in NR2A and NR2B subunit expression. Deletion of the NR2 C-terminal ESDV motifs resulted in the loss of this increase following coexpression of NR1-1a/NR2A(Trunc) and NR1-1a/NR2B(Trunc) with PSD-95. Characterisation of the radioligand binding properties of [(3)H]MK-801 to NR1-1a/NR2A receptors with or without PSD-95 showed that PSD-95 induced a threefold increase in B:(max) values and an apparent approximately fivefold decrease in affinity in the presence of 10 microM: L-glutamate. In the presence of 1 mM: L-glutamate, the K:(i) for MK-801 binding to NR1-1a/NR2A with PSD-95 was not significantly different from that for NR1-1a/NR2A without PSD-95. The EC(50) value for the enhancement of [(3)H]MK-801 binding by L-glutamate to NR1-1a/NR2A was 1.8 +/- 0.4 (n = 4) and 8.9 (mean of n = 2) microM: in the absence and presence of PSD-95, respectively. Thus, coexpression of PSD-95 with NR1-1a/NR2A results in a decreased sensitivity to L-glutamate and an enhanced expression of NR2A and NR2B subunits. Deletion studies show that this effect is mediated via interaction of the C-terminal ESDV motif of the NR2 subunit with PSD-95.
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London, England.
authors.forename: A R
authors.initials: AR
authors.lastname: Rutter
authors.forename: F A
authors.initials: FA
authors.lastname: Stephenson
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D002478:Cells, Cultured; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D021122:Protein Subunits; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D011869:Radioligand Assay; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
chemical_list: D018691:Excitatory Amino Acid Antagonists; D007211:Indoles; C101788:MDL 105519; C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D009419:Nerve Tissue Proteins; D021122:Protein Subunits; D016271:Proto-Oncogene Proteins c-myc; D016194:Receptors, N-Methyl-D-Aspartate; C033652:postsynaptic density proteins; D018698:Glutamic Acid; D016291:Dizocilpine Maleate