HDAC5 is a member of the class II mammalian histone deacetylase family, which is structurally related to yeast HDA1. Human HDAC5 is composed of 1122 amino acid residues. The deacetylase domain of HDAC5 is located at the C-terminal half of the molecule. The N-terminal non-deacetylase domain does not show any significant homology with any published sequence.Both domains are required for HDAC5-mediated repression of gene transcription. HDAC5 interacts with a growing number of transcriptional factors including MEF2A as well as other HDAC proteins. The interacting complexes bind to specific regions of chromatin and regulate gene transcription in these regions.