Responsible for the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4) (PubMed:10220385). Histone deacetylation gives a tag for epigenetic repression and plays an important role in transcriptional regulation, cell cycle progression and developmental events (PubMed:10220385). Histone deacetylases act via the formation of large multiprotein complexes (PubMed:10220385). In addition to histones, deacetylates other proteins: plays a central role in microtubule-dependent cell motility by mediating deacetylation of tubulin (PubMed:12024216, PubMed:20308065). Promotes deacetylation of CTTN, leading to actin polymerization, promotion of autophagosome-lysosome fusion and completion of autophagy (PubMed:30538141). Involved in the MTA1-mediated epigenetic regulation of ESR1 expression in breast cancer (PubMed:24413532). In addition to its protein deacetylase activity, plays a key role in the degradation of misfolded proteins: when misfolded proteins are too abundant to be degraded by the chaperone refolding system and the ubiquitin-proteasome, mediates the transport of misfolded proteins to a cytoplasmic juxtanuclear structure called aggresome (PubMed:17846173). Probably acts as an adapter that recognizes polyubiquitinated misfolded proteins and target them to the aggresome, facilitating their clearance by autophagy (PubMed:17846173). H2O + N(6)-acetyl-L-lysyl-[histone] = acetate + L-lysyl-[histone] H2O + N(6)-acetyl-L-lysyl-[alpha-tubulin] = acetate + L-lysyl-[alpha-tubulin] Binds 3 Zn(2+) ions per subunit. Interacts with SIRT2 (via both phosphorylated, unphosphorylated, active or inactive forms); the interaction is necessary for the complex to interact with alpha-tubulin (PubMed:12620231, PubMed:17516032). Under proteasome impairment conditions, interacts with UBD via its histone deacetylase 1 and UBP-type zinc-finger regions (PubMed:19033385, PubMed:25422469). Interacts with BBIP1, CBFA2T3, CYLD, DDIT3/CHOP, ZMYND15, F-actin and HDAC11 (PubMed:19893491, PubMed:11533236, PubMed:11948178, PubMed:19081074, PubMed:17872950). Interacts with RIPOR2; this interaction occurs during early myogenic differentiation and prevents HDAC6 to deacetylate tubulin (PubMed:24687993). Interacts with DYSF; this interaction occurs during early myogenic differentiation (PubMed:24687993). Interacts with TPPP; inhibiting the tubulin deacetylase activity of HDAC6 (PubMed:20308065, PubMed:23093407). Interacts with DYNLL1 (PubMed:31505170). Interacts with ATP13A2; the interaction results in recruitment of HDAC6 to lysosomes to promote CTTN deacetylation (PubMed:30538141). It is mainly cytoplasmic, where it is associated with microtubules. Phosphorylated by AURKA. Ubiquitinated. Its polyubiquitination however does not lead to its degradation. Sumoylated in vitro. The disease is caused by variants affecting the gene represented in this entry. Required for TGF-beta1-activated gene expression associated with epithelial-mesenchymal transition (EMT) in A549 cells. Belongs to the histone deacetylase family. HD type 2 subfamily. Extended N-terminus.