(a) Model of the cohesin complex and Scc2 based on crystal structures (Scc2 (PDB: 5T8V), Smc1-Scc1 interface (PDB: 1W1W), Smc3-Scc1 interface (PDB: 4U × 3), Smc3-Smc1 interface (PDB: 2WD5), Scc3 (PDB: 4PJU), coiled coil of Smc3 and Smc1 modelled on dynein (PDB: 3WUQ), Scc1 central domain modelled from Scc2 N terminus (PDB: 4XDN). (b) Illustration to demonstrate the formation of TADs by loop extrusion. Loops are progressively enlarged until they reach convergent CTCF sites. (c) Z-projected images from a time-lapse confocal microscopy recording of JF549-Halo-Scc2 (Scc2JF549) in HeLa cells. Time 0 hr = interphase, 6.5 hr = prophase, 7.75 hr = metaphase, 8 hr = telophase and 8.25 hr = G1. Scale bar = 5 µm. (d) FACS analysis of cells stained with propidium iodide either 6 hr (G2) or 15 hr (G1) after release from a double thymidine block, and cycling cells. (e) Still images from a fluorescence recovery after photobleaching (FRAP) experiment. Dashed circle represents bleached region. (f) FRAP curves of Scc2JF549 in G1 and G2. Error bars denote standard error of the mean (s.e.m.). (g) Mean half-life of chromatin bound Scc2JF549 derived from bi-exponential curve fitting of individual experiments from cells in G1 and G2. Error bars denote s.e.m. Unpaired t-test was used to compare conditions. n = 14 cells per condition.