UAS regulatory sequences (from pWalium10.moe) drive expression of an unanchored, uncleavable chain of six tandem copies of Ubiquitin; the chain lacks the internal "GG" motifs that are necessary for isopeptide bond formation and dismantling by deubiquitinases. The poly-Ubiquitin chain also lacks a terminal "GG", meaning that the chain cannot itself be conjugated onto other proteins. All Lys residues within the chain have been mutated to the similar, but non-ubiquitinatable, amino acid Arg to prevent ubiquitination. Each copy of Ubiquitin within the chain also carries a I44A amino acid replacement; this mutation has previously been used to disrupt the hydrophobic patch. The coding sequence is tagged at the N-terminal end with Tag:polyHis.