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. H3.1 is enriched in PTMs associated with gene activation （K14 acetylation） and gene silencing （K9 dimethylation）, suggesting that these mammalian H3 variants may, indeed, have separate biological functions.