HDACs are classified into four main classes based on their structure and function:
1. Class I HDACs: Includes HDAC1, HDAC2, HDAC3, and HDAC8. These are primarily localized in the nucleus and are involved in gene repression. 2. Class II HDACs: Divided into Class IIa (HDAC4, HDAC5, HDAC7, HDAC9) and Class IIb (HDAC6, HDAC10). These can shuttle between the nucleus and cytoplasm. 3. Class III HDACs: Also known as sirtuins (SIRT1-7), these are NAD+-dependent enzymes and have roles in metabolism and aging. 4. Class IV HDACs: Includes only HDAC11, which shares properties with both Class I and II HDACs.
