Histone H2B type 1-A

UniProtKB accession:  P70696

Grouped By:  Matching UniProtKB accession

UniProtKB description:  Variant histone specifically required to direct the transformation of dissociating nucleosomes to protamine in male germ cells (PubMed:23884607, PubMed:28366643). Entirely replaces classical histone H2B prior nucleosome to protamine transition and probably acts as a nucleosome dissociating factor that creates a more dynamic chromatin, facilitating the large-scale exchange of histones (PubMed:23884607). In condensing spermatids, the heterodimer between H2AB1 and H2BC1/TH2B is loaded onto the nucleosomes and promotes loading of transition proteins (TNP1 and TNP2) onto the nucleosomes (PubMed:28366643). Inclusion of the H2AB1-H2BC1/TH2B dimer into chromatin opens the nucleosomes, releasing the nucleosomal DNA ends and allowing the invasion of nucleosomes by transition proteins (TNP1 and TNP2) (PubMed:28366643). Then, transition proteins drive the recruitment and processing of protamines, which are responsible for histone eviction (PubMed:28366643). Also expressed maternally and is present in the female pronucleus, suggesting a similar role in protamine replacement by nucleosomes at fertilization (PubMed:23884607). 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.