Chromatin modifiers are a large and varied group of proteins that conduct a wide range of epigenetic functions. The ability to bind DNA, adjust chromatin conformation and modify histones allows them to influence gene expression making them powerful targets for epigenomic research and potential therapeutic targets.
Chromatin Modifying Protein Classes
Polycomb group proteins (PcG): Are responsible for cellular differentiation during development via transcriptional repression. These proteins have been the subject of intense study as it is clear that they are vital for maintenance of cell-type identity, differentiation, and disease by creating and maintaining repressive chromatin environments by forming one of two major polycomb repressive complexes (PRC): PRC1, and PRC2.
Heterochromatin protein 1 (HP1): It doesn’t take a PhD is biochemistry to guess what heterochromatin protein 1 (HP1) does. HP1 is a family of three proteins that are vital for the formation of transcriptionally inactive heterochromatin.
Zinc finger (ZnF) proteins: Are a massive, diverse family of proteins that serve a wide variety of biological functions.The zinc ion serves to stabilize the integration of the protein itself, and is generally not involved in binding targets. The “finger” refers to the secondary structures (α-helix and β-sheet) that are held together by the Zn ion. Zinc fingers typically serve as interactors, binding DNA, RNA, proteins or small molecules
Histone acetyltransferases (HATs): These enzymes have a huge role epigenetic regulation of gene expression. They catalyze the transfer of an acetyl group from acetyl-CoA to ε-amino group of a histone lysine residue. These acetylations then serve allow transcriptional access to DNA by either neutralizing the positive histone change, or serving as a binding site for chromatin remolding complexes.
Histone deacetylases (HDACs): Are responsible for removing the acetyl groups put on histones (and other proteins) by the histone acetyltransferases (HATs). This process is a vital aspect of epigenetic regulation of gene expression and more generally for the control of cellular stability.