Focus on Histones

Histones are a family of proteins which help organise and condense the DNA. Four core histone proteins (H2A, H2B, H3 and H4) make up the histone core around which DNA is wound to form the nucleosome. The DNA between nucelosomes is bound by the linker histone H1. Histone proteins are able to control the level of compaction of the DNA to facilitate gene expression or silencing. CRB offer a wide range of histone peptides including histone variant peptides and highly modified histone peptides. 

The tail region of the four core histone proteins have the ability to be highly modified by a wide range of histone modifying enzymes. Modifications include methylation, acetylation, phosphorylation and ubiqutination and serve to alter the binding of the histones to the DNA making the DNA either open and available to the transcription machinery or closed and inaccessible.