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The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast(More)
1. In outside-out patches excised from human embryonic kidney (HEK) 293 cells expressing Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptor (AMPAR) channels, currents activated by 1 ms glutamate pulses at negative membrane potentials facilitated during and following a repetitive (2 to 100 Hz) agonist application. The degree of(More)
The structure of the NMDA receptor channel M2 segment was investigated by probing the extracellular and cytoplasmic faces of cysteine-substituted NR1-NR2C channels with charged sulfhydryl-specific reagents. The pattern of accessible positions suggests that the M2 segment forms a channel-lining loop originating and ending on the cytoplasmic side of the(More)
In NMDA receptor channels, the M2 loop forms the narrow constriction and the cytoplasmic vestibule. The identity of an extracellular vestibule leading toward the constriction remained unresolved. Using the substituted cysteine accessibility method (SCAM), we identified channel-lining residues of the NR1 subunit in the region preceding M1 (preM1), the(More)
1. The molecular determinants for the narrow constriction of recombinant N-methyl-D-aspartate (NMDA) receptor channels composed of wild-type and mutant NR1- and NR2A-subunits were studied in Xenopus oocytes. 2. The relative permeability of differently sized organic cations was used as an indicator of the size of the narrow constriction. From measured(More)
The actions of N-ethylmaleimide (NEM), a sulfhydryl alkylating agent, on G-protein-mediated inhibition of N-type Ca2+ channels in adult rat superior cervical ganglion (SCG) neurons were studied using whole-cell voltage clamp. In SCG neurons, inhibition of ICa occurs by at least three separable pathways: one pertussis toxin (PTX) sensitive and voltage(More)
The channels associated with glutamate receptor (GluR) subtypes, namely N-methyl-D-aspartate receptors (NMDARs), and Ca(2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) and kainate receptors (KARs), are to varying degrees permeable to Ca(2+). To compare the mechanism of Ca(2+) influx, we measured Ca(2+) permeability(More)
1. The voltage-dependent block of N-methyl-D-aspartate (NMDA) receptor channels by extracellular Mg2+ is a critical determinant of its contribution to CNS synaptic physiology. The function of the narrow constriction of the channel in determining the block was investigated by analysing the effects of a set different amino acid substitutions at exposed(More)
Functional N-methyl-D-aspartate receptors (NMDARs) are heteromultimers formed by NR1 and NR2 subunits. The M3 segment, as contributed by NR1, forms the core of the extracellular vestibule, including binding sites for channel blockers, and represents a critical molecular link between ligand binding and channel opening. Taking advantage of the substituted(More)
1. N-methyl-D-aspartate (NMDA) receptor channels are blocked by intracellular Mg2+ in a voltage-dependent manner. Amino acid residues positioned at or near the narrow constriction that interact with intracellular Mg2+ were identified in recombinant NR1-NR2A channels expressed in Xenopus oocytes or human embryonic kidney (HEK) 293 cells. 2. In the absence of(More)