Histone variants and complexes involved in their exchange.

In contrast to canonical histones, which are assembled into nucleosomes during DNA replication, histone variants can be incorporated into specific regions of the genome throughout the cell cycle. Recent findings suggest that histone variants associate with factors mediating their deposition into specialized chromatin domains. The mechanisms of their targeted deposition, their turnover, and their posttranslational modification are not yet fully understood. Emerging evidence indicates that histone variants and associated factors are essential for the epigenetic control of gene expression and other cellular responses. Thus, histone variants and complexes involved in their exchange are likely to play major roles in controlling chromosomal architecture, and their deregulation is expected to be linked to cancers, infertility, mental disorders, ageing, and degenerative diseases.