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. Author manuscript; available in PMC: 2008 Jun 15.
Published in final edited form as: Neuroscience. 2007 May 23;147(1):164–173. doi: 10.1016/j.neuroscience.2007.02.063

Figure 1. Schematic representations of the proposed structure of the NMDA receptor channel subunits and the NR1 subunit splice variant composition.

Figure 1

(A) Schematic representation of the proposed structure of the NMDA receptor channel subunits NR1 and NR2. The NR1 three transmembrane segment topology model shows the transmembrane domains in red and the alternatively spliced cassettes; N1 (yellow triangle), C1 (dark blue cylinder) and C2 (orange cylinder). Adapted from Yamakura and Shimoji 1999. (B) Detailed scheme of splice variant composition of NR1 protein. Colored boxes indicate the four alternatively spliced cassettes of NR1 protein, along with their name and exon number. The N1 cassette (exon 5) is extracellular at the N-terminal (solid yellow box). The red bars indicate the four transmembrane (M1, 3 and 4) or intramembrane (M2) domains of the NR1 protein. The three C-terminal cassettes; C1 (blue diamonds filled box), C2 (orange grid filled box) and C2′ (vertical green lines filled box) are located intracellularly (Prybylowski et al. 2001). (C) Splice variants of the NR1 subunit. The eight splice variants of the NR1 protein in the presence (+) or absence (−) of three alternatively spliced exons (N1, C1 and C2); NR1xyz, where x, y and z represent the cassettes N1, C1 and C2, respectively. The values of x, y and z are either 0 or 1 indicating the absence or presence of the respective cassette (Durand, Bennett and Zukin 1993).