It is true that the local resolution of some parts of the map, especially the loops connecting the long β-strands and one loop in the periphery of domain 4, is worse than 4.5 Å, but the resolution of domains 1, 2 and parts of domain 4 is significantly better. The local resolution estimate (new Figure 1—figure supplement 3) shows this clearly for the whole pore complex and for an individual protomer seen from different directions. The new supplementary figures demonstrate the excellent quality of the map, which resolves many of the tryptophan and tyrosine sidechains (Figure 2—figure supplements 1–3). This would be expected at 4 Å rather than at 4.5 Å resolution.