Cloning and sequence analysis of cDNAs encoding human hippocampus N-methyl-D-aspartate receptor subunits: evidence for alternative RNA splicing

• Published in: Gene Vol. 131; no. 2; p. 293
• Main Authors: Foldes, R L, Rampersad, V, Kamboj, R K
• Format: Journal Article
• Language: English
• Published: Netherlands 15-09-1993
• Subjects: Alternative Splicing; Amino Acid Sequence; Animals; Base Sequence; Cloning, Molecular; DNA; Hippocampus - metabolism; Humans; Molecular Sequence Data; Receptors, N-Methyl-D-Aspartate - genetics; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid
• ISSN: 0378-1119
• DOI: 10.1016/0378-1119(93)90309-Q

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.