Further characterization of the molecular interaction between PSD-95 and NMDA receptors: the effect of the NR1 splice variant and evidence for modulation of channel gating.
Coexpression of PSD-95(c-Myc) with NR1-1a/NR2A NMDA receptors in human embryonic kidney (HEK) 293 cells resulted in a decrease in efficacy for the glycine stimulation of [3 H]MK801 binding similar to that previously described for l-glutamate. The inhibition constants (K (I) s) for the binding of l-glutamate and glycine to NR1-1a/NR2A determined by [3 H]CGP 39653 and [3 H]MDL 105 519 displacement assays, respectively, were not significantly different between NR1-1a/NR2A receptors coexpressed +/- PSD-95(c-Myc). The increased EC(50) for l-glutamate enhancement of [3 H]MK801 binding was also found for NR1-2a/NR2A and NR1-4b/NRA receptors thus the altered EC(50) is not dependent on the N1, C1 or C2 exon of the NR1 subunit. The NR1-4b but not the NR1-1a subunit was expressed efficiently at the cell surface in the absence of NR2 subunits. Total NR1-4b and NR1-4b/NR2A expression was enhanced by PSD-95(c-Myc) but whole cell enzyme-linked immunoadsorbent assays (ELISAs) showed that this increase was not due to increased expression at the cell surface. It is suggested that PSD-95(c-Myc) has a dual effect on NMDA receptors expressed in mammalian cells, a reduction in channel gating and an enhanced expression of NMDA receptor subunits containing C-terminal E(T/S)XV PSD-95 binding motifs.
Rutter
A Richard
AR
Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London, UK.
Freeman
Fiona M
FM
Stephenson
F Anne
FA
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives* / Q000378:metabolism; D001667:Binding, Competitive; D002460:Cell Line; D004274:DNA, Recombinant; D016291:Dizocilpine Maleate / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism; D014644:Genetic Variation / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000494:pharmacology / Q000502:physiology*; D016548:Prosencephalon / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D004274:DNA, Recombinant; D018691:Excitatory Amino Acid Antagonists; C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; D009419:Nerve Tissue Proteins; D016194:Receptors, N-Methyl-D-Aspartate; C033652:postsynaptic density proteins; C069052:CGP 39653; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate; D005998:Glycine