The NMDA receptor M3 segment is a conserved transduction element coupling ligand binding to channel opening.
Ion channels alternate stochastically between two functional states, open and closed. This gating behavior is controlled by membrane potential or by the binding of neurotransmitters in voltage- and ligand-gated channels, respectively. Although much progress has been made in defining the structure and function of the ligand-binding cores and the voltage sensors, how these domains couple to channel opening remains poorly understood. Here we show that the M3 transmembrane segments of the NMDA receptor allosterically interact with both the ligand-binding cores and the channel gate. It is proposed that M3 functions as a transduction element whose conformational change couples ligand binding with channel opening. Furthermore, amino acid homology between glutamate receptor M3 segments and the equivalent S6 or TM2 segments in K(+) channels suggests that ion channel activation and gating are both structurally and functionally conserved.
Jones
Kevin S
KS
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
VanDongen
Hendrika M A
HM
VanDongen
Antonius M J
AM
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D017124:Conserved Sequence / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005020:Ethyl Methanesulfonate / Q000031:analogs & derivatives* / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008024:Ligands; D008845:Microinjections; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology; D018075:RNA, Complementary / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
D018690:Excitatory Amino Acid Agonists; D008024:Ligands; D015221:Potassium Channels; D018075:RNA, Complementary; D016194:Receptors, N-Methyl-D-Aspartate; C093171:methanethiosulfonate ethylammonium; D018698:Glutamic Acid; D005020:Ethyl Methanesulfonate; D005998:Glycine