“…[2,6,7] Numerous biochemical data, [8,9] hydropathy assignments and structural data from electron microscopy [10±12] and NMR spectroscopy [13±17] have led to the current four-transmembrane-helix model for ion channels that are nicotinic acetylcholine receptor like (Figure 2 D). [2,8,9] While ionotropic glutamate receptors also belong among the group of directly ligand gated ion channels, they are structurally more closely related to the voltage-gated receptor family. [2,18] Nmethyl-D-aspartate (NMDA) receptors, a subclass of the glutamate-receptor family, carry a glycine binding site and are sometimes referred to as 'non-strychnine-sensitive glycine receptors' in the literature, although in this case glycine modulates the receptor function through an allosteric site and does not actually gate the ion channel.…”