The FSC curve between the model and the map is now included in Figure 1—figure supplement 2B (blue curve). Note that the model was used as built into the map, but not refined, for the reasons given below. Like the masked FSC, this curve shows a sharp peak at 4.8 Å, due to the strong contribution of the resolved long β hairpins in the barrel. The correlation factor at the steep drop beyond this peak at 4.5 Å is not 0.5 (which is an arbitrary value), but approximately 0.3. We draw the reviewers’ and editor’s attention to two papers, which will be familiar to the BRE of our study, that report similar thresholds for the map against model FSC of the 3.4 Å structure of the ribosome/Sec61 complex (Voorhees et al., Cell 2014) and the tri-snRNP spliceosome at 5.9 Å (Nguyen et al., Nature 2015).