Histone deacetylase (HDAC) and histone acetyltransferase (HAT) are enzymes that regulate transcription by selectively deacetylating or acetylating the ε-amino groups of lysines located near the amino termini of core histone proteins. Eleven members of HDAC family have been identified in the past several years. These HDAC family members are divided into two classes, I and II. HDAC4 is a member of the class II family which also includes HDACs 5, 6, and 7, the molecular weights of which are all about two-fold larger than those of the class I members.
