3D classification ORCO2WH was performed with the density map low-pass filtered to 20 Å and an E-step resolution limit of 20 Å. Two 3D classes from ORCO2WH contained densities for ORC1 AAA+ domain. The ORC1 AAA+ domain was fit into these densities which revealed the domain approaching the ORC1·4 position (a) and the auto-inhibited position (b). (c-f) In the ORC core, the ORC2 WHD was observed in two conformations: an alternate state, called the inactive state (c, e), and the auto-inhibited state (f), similar to the DmORC2 WHD (PDB ID: 4xgc) (d). The ORCO2WH inactive state (e) was determined by focused classification of the ORCO2WH with a tight mask around ORC2 WH.