Cloning of cDNA for the glutamate-binding subunit of an NMDA receptor complex

Abstract

The amino acids L-glutamic and L-aspartic acids form the most widespread excitatory transmitter network in mammalian brain. The excitation produced by L-glutamic acid is important in the early development of the nervous system, synaptic plasticity and memory formation, seizures and neuronal degeneration. The receptors activated by L-glutamic acid are a target for therapeutic intervention in neurodegenerative diseases, brain ischaemia and epilepsy. There are two types of receptors for the excitatory amino acids, those that lead to the opening of cation-selective channels and those that activate phospholipase C (ref. 11). The receptors activating ion channels are NMDA (N-methyl-D-aspartate) and kainate/AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate)-sensitive receptors. The complementary DNAs for the kainate/AMPA receptor and for the metabotropic receptor have been cloned. We report here on the isolation and characterization of a protein complex of four major proteins that represents an intact complex of the NMDA receptor ion channel and on the cloning of the cDNA for one of the subunits of this receptor complex, the glutamate-binding protein.

Basic FGF regulates the expression of a functional 71 kDa NMDA receptor protein that mediates calcium influx and neurotoxicity in hippocampal neurons

“…Oligonucleotide stocks were prepared in sterile water at concentrations of l-2 mM. The oligonucleotides used in the present study included NMDARP-71 (Kumar et al, 1991) antisense 1 (AS l), 5'-GAGGGCTGGAAAGCGGCCTGT-3'; NMDARP-7 1 antisense 2 (AS2), 5'-GAAACTCTTTTCATGGTACA-3'; NMDARP-7 1 sense, 5'-ACAGGCCGCTTTCCAGCCCTC-3'.…”

“…Recently, a putative NMDA receptor protein complex was isolated from rat brain synaptic membranes (Ikin et al, 1990;Kumar et al, 199 1;Ly and Michaelis, 199 1) and the cDNA for a 71 kDa subunit of this complex (NMDARP-71) was cloned (Kumar et al,199 1). Protein reconstitution and pharmacological studies suggest that NMDARP-7 1 is the glutamate-binding subunit of a complex of four proteins that comprise a functional NMDA receptor-ion channel (Kumar et al, 1991;Ly and Michaelis, 199 1;Minami et al, 199 1). The latter conclusion is consistent with molecular characterizations of the NMDA receptor through the use of conotoxins, as well as electrophysiological characterization of the NMDA receptor (Ascher and Nowak, 1987; Clements and Westbrook, 199 1).…”

Adult bone marrow stromal stem cells express germline, ectodermal, endodermal, and mesodermal genes prior to neurogenesis

“…Likewise, ectodermal syntaxin 13, highly enriched in the brain (Advanti et al, 1998), and brain-specific aldolase C (Mukai et al, 1991) are expressed by MSCs. NMDA glutamate binding protein (Kumar et al, 1991) and APP (Shivers et al, 1988) represent additional neural genes transcribed by MSCs. These observations are consistent with our previous finding that the MSCs express low levels of NSE (Woodbury et al, 2000).…”

Ion channel properties of a protein complex with characteristics of a glutamate/N‐methyl‐d‐aspartate receptor

“…However, it does not contain the NMDAR1 protein, the key subunit of NMDAR that is absolutely necessary for the expression of receptor activity in complexes formed of the NMDAR1 and NMDAR2 subunits [10 12]. The cDNAs for the L-Glu-binding and Gly/TCP-binding proteins have no significant homology to any previously cloned L-Glu receptor, L-Glu transport, or L-Glu-metabolizing enzyme proteins [13,14]. Therefore, even though this complex of proteins may be easily purified, its potential function as an ion channel-forming L-Glu receptor is not certain.…”