UAS regulatory sequences drive expression of the Scr C terminus containing the YPWM motif and the homeodomain (HD). The homeodomain carries amino acid substitutions T6D and S7D (these mutations have been shown to result in an inactive variant in the full-length protein and they behave in a similar manner in the truncated peptide).
Expression of the constitutively inactive ScrDD.Scer\UAS under the control of Scer\GAL4hs.PB fails to induce ectopic salivary glands in the embryonic head. The embryos expressing ScrDD.Scer\UAS display a normal pair of salivary glands, similar to that of controls.
Ectopic expression of ScrDD.Scer\UAS under the control of Scer\GAL4Dll-md23 is unable to induce a reduction in the size of the arista as compared to the wild-type antenna.
No abnormal eye phenotype is observed with Scer\GAL4dpp.blk1>ScrDD.Scer\UAS. The eyes of flies expressing ScrDD.Scer\UAS are indistinguishable from wild-type.