Figure 1. W68 is highly conserved.

A, sequence alignment for Kir channels showing the conservation of tryptophan at the residue equivalent to W68 in Kir6.2. The tryptophan residue is not conserved in the majority of other K⁺ channel species. B, model of Kir6.2 showing the location of W68 (red). The slide helix is coloured blue. The transmembrane gate is formed by the C-terminal end of TM2 and is shown in green. The putative bound conformations for ATP (cyan) (Antcliff et al. 2005) and PIP₂ (yellow) (Stansfeld et al. 2009) are shown as sticks.