Figure 2
Crystal structures of ELIC with isoflurane bound within the pore.
Side views of ELIC bound with two isoflurane molecules near residues T237(6′) and A244(13′) in (a) the resting and (b) desensitized states. The FΟ-FC omitted electron density maps (green) are contoured at 5.0 σ level with a carve distance of 1.8 Å for isoflurane molecules. Two inserted top views in (a) show 2FΟ-FC electron density maps contoured at 1.0 σ level for isoflurane bound to the 13′ and 6′ positions of ELIC in the resting conformation. (c) ELIC residues within 4 Å in contact with isoflurane: T237(6′), green; L240(9′), black; and A244(13′), magenta. Dashlines highlight potential hydrogen bonding between isoflurane and T237(6′). (d) Isoflurane binding induced an inward movement of the upper portion of TM2 and reduced pore radius near 16′. The pore profile of apo ELIC (black), ELIC-isoflurane (magenta), ELIC-isoflurane-agonist 3-bromopropylamine (cyan) were calculated using the HOLE program70 based on their crystal structures (PDB codes: 3RQU, 4Z90, 4Z91). The z-coordinate is parallel to the channel axis and the zero point of the pore radius is overlapped with the channel axis.
