N2904-20B

Rabbit Anti-NMDA 1 Receptor, N1 Splice Variant (NMDA R1, N-methyl-D-aspartate)

NMDA (N-Methyl D-Aspartate) receptors are members of the glutamate receptor family of ligand-gated ion channels. The functional NMDA receptor is a heteromultimer of at least two NR1 (NMDA receptor-1) subunits and two NR2 subunits. Regulation of the NMDA complex by external factors such as zinc, PKC and polyamines is mediated by NR1 subunits. Upon glycine binding to NR1, and glutamate binding to NR2, the NMDA channel is opened, allowing calcium and sodium influx into the cell. NR1 is a 120 kD, 938 amino acid (aa), three transmembrane (TM) glycoprotein that contains a 541 aa extracellular domain and a 105 aa cytoplasmic region. The molecule is described as 4-TM. However, the second-TM segment is only partial (or reenterant), and this makes the C-terminus intracellular. Differential splicing of three exons generates up to nine isoforms of NR1. These exons encode a 21 amino acid N-terminal domain (N1) and adjacent sequences in the C-terminus (C1 and C2). Splicing out the C2 cassette eliminates the first stop codon and produces a new reading frame that generates a new sequence of 22 amino acids (C2'). Eight are integral membrane proteins. At the N-terminus, four isoforms show a 21 aa insertion between aa 190-191, and four do not. This is compounded by at least four possible variants between aa 864-938 in the cytoplasmic tail that impact potential serine phosphorylation sites. To date, all are believed to be physiologically active. There is one potentially "soluble" form that is only 181 aa in length. Its function is unknown.