Divergent roles of a peripheral transmembrane segment in AMPA and NMDA receptors

Amin, J. B., Salussolia, C. L., Chan, K., Regan, M. C., Dai, J., Zhou, H. X., Furukawa, H., Bowen, M. E., Wollmuth, L. P. (2017) Divergent roles of a peripheral transmembrane segment in AMPA and NMDA receptors. J Gen Physiol, 149 (6). pp. 661-680. ISSN 0022-1295

URL: https://www.ncbi.nlm.nih.gov/pubmed/28507080
DOI: 10.1085/jgp.201711762

Abstract

Ionotropic glutamate receptors (iGluRs), including AMPA receptor (AMPAR) and NMDA receptor (NMDAR) subtypes, are ligand-gated ion channels that mediate signaling at the majority of excitatory synapses in the nervous system. The iGluR pore domain is structurally and evolutionarily related to an inverted two-transmembrane K+ channel. Peripheral to the pore domain in eukaryotic iGluRs is an additional transmembrane helix, the M4 segment, which interacts with the pore domain of a neighboring subunit. In AMPARs, the integrity of the alignment of a specific face of M4 with the adjacent pore domain is essential for receptor oligomerization. In contrast to AMPARs, NMDARs are obligate heterotetramers composed of two GluN1 and typically two GluN2 subunits. Here, to address the function of the M4 segments in NMDARs, we carry out a tryptophan scan of M4 in GluN1 and GluN2A subunits. Unlike AMPARs, the M4 segments in NMDAR subunits makes only a limited contribution to their biogenesis. However, the M4 segments in both NMDAR subunits are critical for receptor activation, with mutations at some positions, most notably at the extreme extracellular end, completely halting the gating process. Furthermore, although the AMPAR M4 makes a minimal contribution to receptor desensitization, the NMDAR M4 segments have robust and subunit-specific effects on desensitization. These findings reveal that the functional roles of the M4 segments in AMPARs and NMDARs have diverged in the course of their evolution and that the M4 segments in NMDARs may act as a transduction pathway for receptor modulation at synapses.

Item Type: Paper
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > AMPA receptor
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > NMDA receptor
CSHL Authors:
Communities: CSHL labs > Furukawa lab
Depositing User: Matt Covey
Date Deposited: 19 May 2017 20:18
Last Modified: 21 Jul 2017 14:52
PMCID: PMC5460951
Related URLs:
URI: http://repository.cshl.edu/id/eprint/34795

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