This domain is found at the C-terminus of many NMDA-receptor proteins, many of which also carry the Ligated ion-channel family Pfam:PF00060 further upstream as well as the ANF_receptor family Pfam:PF01094. This region is predicted to be a large extra-cellular domain of the NMDA receptor proteins, being highly hydrophilic, and is thought to be integrally involved in the function of the receptor. The region also carries a number of potential N-glycosylation sites [1].

1: Molecular characterization of the family of the N-methyl-D-aspartate receptor subunits. Ishii T, Moriyoshi K, Sugihara H, Sakurada K, Kadotani H, Yokoi M, Akazawa C, Shigemoto R, Mizuno N, Masu M, et al.; J Biol Chem. 1993;268:2836-2843. PMID:8428958

2: Interaction between the C terminus of NMDA receptor subunits and multiple members of the PSD-95 family of membrane-associated guanylate kinases. Niethammer M, Kim E, Sheng M; J Neurosci. 1996;16:2157-2163. PMID:8601796

3: Molecular characterization and embryonic expression of the family of N-methyl-D-aspartate receptor subunit genes in the zebrafish. Cox JA, Kucenas S, Voigt MM; Dev Dyn. 2005;234:756-766. PMID:16123982