Extended Data Fig. 5: Properties of Klf4 clusters on DNA.

a, Confocal images of representative time lapses of the four types of fusion events observed (i-iv). (i) corresponds to Fig. 1i. b, Intensity profiles along the DNA before (black) and after (red) fusion. The events were classified into adsorbed-adsorbed (i, ii, N = 9); adsorbed-condensed (iii, N = 9) and condensed-condensed (iv, N = 12). Blue shade and dotted line, intensity region corresponding to the adsorbed state. c, Histogram of the ratio of number of molecules before and after fusion. d, Representative confocal microscopy images of the time course of a FRAP experiment. Time stamps are referenced to the time of induced photo-bleaching. e, Mean intensity across the FRAP ROI corrected for photo-bleaching. Individual traces of mean intensity in the FRAP ROI were divided by the mean intensity in the non-FRAP ROI (cyan squares in d) and normalized to the value prior to the photo-bleaching step. Black line shows the average trace for N = 13 experiments, grey shade, standard error of the mean at 95% confidence. f, Kymograph showing the displacement of Klf4-GFP clusters along the DNA. In red, the trajectories of segmented clusters are shown. Segmentation was done using the python package Trackpy (see Supplementary Methods) with initial search parameters of P_R = 15 pixels, S_R = 6 pixels, t_memory = 30 s and t_min = 100 s. g, Position of foci over time along the DNA relative to the initial point of each trace (Position = x(t) -x(t = 0), where x(t) is the position over time). A random selection of 50 traces is shown. h, Histogram of the maximum excursion length (defined as the farthest point a cluster moves from the initial position. The number of traces (N_trace) is indicated. N = 168 experiments were considered for [Klf4] =3–281 nM.