Four data collections were performed, resulting in 14,201 micrographs. These micrographs were aligned using MotionCor2 (ref. 21) with dose weighting, and imported into Relion2.1 (ref. 23) for further processing. Autopicking followed by manual cleaning, 2D and 3D classification produced a total of 514,746 ‘good’ particles. These particles were refined to produce the core map. Further 3D classification without and with alignment was used to obtain the state 1, state 2, state 2A and state 3 maps. Density regions corresponding to domain III (red), domain VI (blue) and Mak11 (green) are highlighted.