A novel class II histone deacetylase, HDAC10 is most similar to HDAC6. Both contain a unique, putative second catalytic domain not found in other HDACs. In HDAC10, however, this domain is not functional. Unlike HDAC6, which is normally a cytoplasmic deacetylase, HDAC10 resides in both the nucleus and cytoplasm. Data suggests that HDAC10 may play roles both in the nucleus, as a transcriptional modulator, and in the cytoplasm in an unidentified role. HDAC10 variants seem present in certain cell lines and tissues that are as of yet not characterized..