a, Schematic model of the S. cerevisiae condensin holo complex and 8.1 Å-resolution 3D map, showing its overall architecture. b, Representative 2D class average of the 5-subunit ‘pentamer’ holo complex in non-engaged and bridged states. c, Representative 2D class average of the 4-subunit ‘tetramer’ complex lacking Ycg1. d, Composite cryo-EM maps of the condensin complex in non-engaged and bridged apo states.