UAS regulatory sequences drive expression of a truncated portion of Hsap\ATXN3; contains the UIM1, UIM2, polyglutamine repeat (polyQ) and UIM3 regions. The polyQ repeat has an expanded length of 80 residues and is encoded by CAGCAA doublet repeats, rather than a pure CAG tract, to avoid the possibility of repeat-associated non-ATG (RAN) translation and mRNA toxicity. The open reading frame is tagged with Tag:HA.