UAS sequences drive expression of a γ-secretase reporter. The reporter consists of a signal sequence and a truncated N sequence (lacking the intracellular domain and most of the extracellular domain) fused to a synthetic lexA-VP16 driver. In the absence of γ-secretase, the lexA-VP16 sequence is tethered at the membrane by the N sequence. In the presence of γ-secretase, intramembrane cleavage releases a fragment that includes the lexA-VP16 driver, allowing expression of lexAop-containing reporter constructs.