To design a PROTAC molecule and determine the optimal linker location, we first analyzed the binding mode of tubastatin A. According to the elucidated crystal structures of Danio rerio HDAC6 (PDB: 6THV) and HDAC10 (PDB: 6WBQ) in complex with tubastatin A, it is evident that tubastatin A exhibits a notable capacity for effective interaction with both targets within their respective catalytic pockets. In the case of HDAC6 (Figure ), the hydroxamic acid group of tubastatin A establishes a hydrogen bond with residue H574 and engages in chelation with the Zn 2+ ion within the catalytic tunnel.