The function of H2BW1 (H2B.W histone 1, Ensembl gene identifier ENSG00000123569) is as follows. Atypical histone H2B that can form nucleosomes structurally and dynamically indistinguishable from those containing conventional H2B. 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 (PubMed:15475252, PubMed:16449661). However, unlike conventional H2B, does not recruit chromosome condensation factors and does not participate in the assembly of mitotic chromosomes (PubMed:16449661). May be important for telomere function and play a role in spermatogenesis (PubMed:16449661, PubMed:19583817). {ECO:0000269|PubMed:15475252, ECO:0000269|PubMed:16449661, ECO:0000269|PubMed:19583817}.