Function
Macronuclear replacement variant which replaces conventional H3 in a subset of nucleosomes. 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. Functions redundantly to H3.4. H3.3 deposition into chromatin is mainly transcription-associated and DNA replication-independent, but it can also enter a replication-coupled pathway. Although not essential for vegetative growth, minor H3 variants are required for producing viable conjugation progeny by affecting late developmental stages of conjugation.