Cloning and sequence analysis of cDNAs encoding human hippocampus N-methyl-D-aspartate receptor subunits: evidence for alternative RNA splicing.
Several cDNA clones encoding human N-methyl-D-aspartate receptor (hNR1) subunit polypeptides were isolated from a human hippocampus library. Degenerate oligodeoxyribonucleotide (oligo) primers based on the published rat NR1 (rNR1) amino acid (aa) sequence [K. Moriyoshi et al. Nature 354 (1991) 31-37] amplified a 0.7-kb fragment from a human hippocampus cDNA library, via the polymerase chain reaction (PCR). This fragment was used as a probe for subsequent hybridization screening. DNA sequence analysis of 28 plaque-purified clones indicated three distinct classes, designated hNR1-1, hNR1-2 and hNR1-3, presumably generated by alternative RNA splicing. One of these clones, hNR1-1(5A), was isolated as a full-length cDNA. The hNR1-2 and hNR1-3 cDNAs represented 66.8 and 98.9%, respectively, of the total aa coding information predicted for the polypeptides. The hNR1 cDNAs demonstrated an 84-90.8% nucleotide (nt) identity with the corresponding rodent cDNAs. The nt sequences of hNR1-1, hNR1-2 and hNR1-3 would encode 885-, 901- and 938-aa proteins, respectively, that have 99.1-99.8% identity with the corresponding rodent NR1 (roNR1) subunits. The changes between the predicted aa sequences of hNR1 and the corresponding roNR1 subunits are confined to the extracellular N-terminal regions. We have also identified two possible allelic variations of the hNR1-3 cDNA that result in aa substitutions in the extracellular N- and C-terminal regions. One of these naturally occurring aa variations is situated within a potential glutamate-binding site.
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Allelix Biopharmaceuticals Inc., Mississauga, Ontario, Canada.
Rampersad
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Kamboj
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D016194:Receptors, N-Methyl-D-Aspartate; D004247:DNA