HDACs are classified into four main classes based on their homology to yeast deacetylases and their cellular localization:
Class I HDACs: These are primarily nuclear enzymes that include HDAC1, HDAC2, HDAC3, and HDAC8. They are involved in the regulation of cell cycle and differentiation. Class II HDACs: These enzymes can shuttle between the nucleus and cytoplasm and include HDAC4, HDAC5, HDAC6, HDAC7, HDAC9, and HDAC10. They play roles in muscle differentiation and immune responses. Class III HDACs: Also known as sirtuins, these NAD+-dependent deacetylases are involved in metabolic regulation and stress responses. Class IV HDACs: This class is represented by a single enzyme, HDAC11, which shares properties with both Class I and II HDACs.
