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, although experiments in vivo show it is itself ubiquitinated in transgenic flies. The coding sequence is tagged at the N-terminal end with Tag:polyHis.