Extended Data Fig. 1: Details of cryo-EM data collection and analysis.

a, Coomassie-stained reducing SDS–PAGE gel of proteins used for the sample preparation. M, molecular weight marker. For gel source data, see Supplementary Fig. 1. b, Representative micrograph of the sample after drift correction and dose weighing. c, Representative 2D class averages. The 2D class averages exhibit different projections corresponding to each orientation. d, 3D classification effectively separated two groups of populations. Left, TfR1–Tf complex with one bound PvRBP2b molecule. Right, TfR1–Tf complex with two bound PvRBP2b molecules. Blue, TfR1–Tf; pink, PvRBP2b. Scale bar, 10 Å. e, Local resolution estimation diagram of the final refined maps. Left, the one-ligand complex; right: the two-ligand complex. Resolution keys are labelled from 3.5 to 6.0 Å. f, Resolution estimation of the cryo-EM map. Fourier shell correlation (FSC) plot showing resolutions at 0.143 FSC (dashed line) for both complexes, determined by the gold-standard method. g, Representative cryo-EM density for different parts of the C-terminal domain of PvRBP2b. Selected residues are also indicated. h, FSC curves of the final refined model versus the final cryo-EM map (full dataset, blue), of the outcome of model refinement with a half map versus the same map (red), and of the outcome of model refinement with a half map versus the other half map (green). In a–c, the experiment was performed once.