Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Component of the UAF (upstream activation factor) complex which interacts with the upstream element of the RNA polymerase I promoter and forms a stable preinitiation complex. Together with SPT15/TBP UAF seems to stimulate basal transcription to a fully activated level. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. The octamer wraps approximately 147 bp of DNA. Histone H4 is a component of the UAF (upstream activation factor) complex which consists of UAF30, RRN5, RRN9, RRN10, and histones H3 and H4. Glutarylation at Lys-92 (H4K91glu) destabilizes nucleosomes by promoting dissociation of the H2A-H2B dimers from nucleosomes. Present with 524000 molecules/cell in log phase SD medium. Belongs to the histone H4 family.