The similarity to histone H1 explains how fork head factors are able to bind chromatin by interacting with the major groove of only the one available side of DNA wrapped around a nucleosome.  Fork head domains also have a helix that confers sequence specificity unlike linker histone.  The C terminus is associated with higher mobility around the nucleosome than linker histone, displacing it and rearranging nucleosomal landscapes effectively.  This active re-arrangement of the nucleosomes allows for other transcription factors to bind the available DNA.  In thyroid cell differentiation FoxE binds to compacted chromatin of the thyroid peroxidase promoter and opens it for NF1 binding.