Fig. 2: OCT4 activation domain remodels the N-terminal tail of histone H4.

a, Overlay of the two distinct conformations of the H4 tail on the OCT4 proximal side of the nucleosome: canonical conformation (blue) and OCT4-remodelled conformation (grey). The interaction of the disordered region of OCT4 (green) with the H4 tail rearranges Asp24, leading to repositioning of the whole tail. b, Mononucleosome compaction by Mg²⁺, assessed by native gel electrophoresis; a representative gel is shown in Extended Data Fig. 5a. Compaction was quantified by the reduction in the intensity of the nucleosome band, due to nucleosome precipitation. Data shown are mean ± s.e.m. of four independent measurements. *P = 0.04 for 2 mM Mg²⁺, ***P = 0.006 for 5 mM Mg²⁺ and ***P = 1.7 × 10⁻⁹ for 10 mM Mg²⁺, one-sided Student’s t-test comparing OCT4-bound nucleosome to nucleosome. c, Quantification of negative-stain EM data showing Mg²⁺-induced compaction of nucleosome arrays assembled on a 1,022-bp-long DNA fragment from the LIN28B locus. The graph shows the distribution of the area occupied (size) by nucleosome arrays, measured from micrographs with the different samples; 300–450 arrays were analysed per sample. Representative micrographs are shown in Extended Data Fig. 5c.