Anti-Histone antibodies are used for the immunodetection of individual protein members of the histone gene family. Histones are a major structural component of nucleosomes that package DNA to form chromatin. Histone modifications, such as acetylation and methylation, influence DNA and protein binding mechanisms thus providing a mode of gene expression. The histones families H2A, H2B, H3 and H4 are known as the core histones, while histones H1 and H5 serve as the linker histones. There are many individual histones in humans; the large histone cluster on chromosome 6, for instance, contains 55 histone genes.