Expression and characterization of a glycine-binding fragment of the N-methyl-D-aspartate receptor subunit NR1

Abstract

N-Methyl--aspartate receptor channels are composed of an NR1 subunit and at least one of the NR2 subunits (NR2A-D). Activation of the N-methyl--aspartate receptor requires the coagonists glycine and glutamate. It has been proposed that the NR1 subunit possesses a glycine-binding site. We have expressed a soluble form of the NR1 subunit, which was produced by connecting the N-terminal extracellular region with the extracellular loop between the third and fourth membrane segments, by a baculovirus system along with full-length and truncated membrane-bound forms. The soluble NR1 receptor was efficiently secreted into the culture medium and showed a high affinity for ligands. The K d of a glycine-site antagonist, [$H]MDL 105,519[(E)-3-(2-phenyl-2-carboxyethenyl)-4,6-dichloro-1H-indole-2-carboxylic acid], for the soluble receptor was 3.89p0.97 nM, which was comparable to the K d of 4.47p1.39 nM for the membrane-bound full-length form. These values were close to the values reported previously with the use

An astroglial basis of major depressive disorder? An overview

“…d ‐serine is principally formed by the racemization of L‐serine by serine racemase (Srr) in astrocytes and is released following glutamate receptor stimulation through a calcium‐ and SNARE‐dependent exocytotic pathway (Martineau, Parpura, & Mothet, ; Martineau et al, ; Mothet et al, ; Wolosker, Blackshaw, & Snyder, ). Glia‐derived d ‐serine is an endogenous coagonist for NMDARs in the brain that binds to the glycine site of the NR1 subunit to facilitate glutamate activation (Miyazaki, Nakanishi, & Jingami, ; Mothet et al, ). d ‐serine controls neural development, synaptic transmission, plasticity and memory (Fossat et al, ; Sultan et al, ).…”

Model structures of the N-methyl-d-aspartate receptor subunit NR1 explain the molecular recognition of agonist and antagonist ligands

“…The antagonist ligand, E-3-(2-phenyl-2-carboxyethenyl)-4,6-dichloro-1-H-indole-2-carboxylic acid (MDL 105,519; (Baron et al, 1996) binds with much higher affinity to NR1 (0.0039 lM) than is reported for glycine (13.82 lM), D D -serine (4.95 lM), and DCKA (0.554 lM) (Miyazaki et al, 1999). MDL 105,519 has a structure similar to DCKA, but an indole ring replaces the quinoline ring.…”

“…Affinity data for NR1, as measured by IC 50 values, have only been reported for expressed S1-S2 constructs ((Ivanovic et al, 1998), S1-S2 domain; (Miyazaki et al, 1999), amino-terminal and S1-S2 domains): D D -serine (10.7; 4.95 lM) was found to be a better ligand than glycine (27; 13.8 lM). Based on the model structures for the agonist complexes, the hydroxyl group of D D -serine (Fig.…”

Molecular pathways responsible for NMDA receptor-mediated behavioural plasticity

“…NMDA receptors composed of NR1 and NR2 subunits combine in a 1:1 ratio and require NR1 to bind two molecules of glycine and NR2 to bind two molecules of glutamate through their respective LBDs (Miyazaki et al 1999;Furukawa & Gouaux 2003;Sobolevsky et al 2009;Vyklicky et al 2014). NR1 and NR2 subunits create a Ca2+ permeable pore with a voltage dependent Mg2+ block (Nowak et al 1984;Chatterton et al 2002).…”