Pioneer factors can also actively affect transcription by directly opening up condensed chromatin in an ATP-independent process.  This is a common trait of fork head box factors (which contain a winged helix DNA-binding domain that mimics the DNA-binding domain of the linker H1 histone), and NF-Y (whose NF-YB and NF-YC subunits contain histone-fold domains similar to those of the core histones H2A/H2B).