Histone deacetylase that catalyzes the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4). Histone deacetylation gives a tag for epigenetic repression and plays an important role in transcriptional regulation, cell cycle progression and developmental events. Histone deacetylases act via the formation of large multiprotein complexes. Also functions as deacetylase for non-histone proteins. In addition to protein deacetylase activity, also has protein-lysine deacylase activity: acts as a protein decrotonylase by mediating decrotonylation ((2E)-butenoyl) of histones. H2O + N(6)-acetyl-L-lysyl-[histone] = acetate + L-lysyl-[histone] H2O + N(6)-acetyl-L-lysyl-[protein] = acetate + L-lysyl-[protein] H2O + N(6)-(2E)-butenoyl-L-lysyl-[protein] = (2E)-2-butenoate + L-lysyl-[protein] Part of a large multiprotein complex that also contains RBBP4. Oocyte. Expressed both maternally and zygotically. Accumulates in previtellogenic oocytes and is maintained at constant level throughout oogenesis and into early embryogenesis. Declines through gastrula to neurula. Not detectable between neurula and tailbud, nor in adult tissues other than ovary. Belongs to the histone deacetylase family. HD type 1 subfamily.