The QUASp entry in FlyBase represents an engineered regulatory region that includes 'QUAS' sequences plus a promoter fragment derived from the P-element transposase gene (P\T), where the P\T fragment includes the 5'UTR in addition to the promoter. The QUAS regulatory sequence present in QUASp is specifically bound by the DNA-binding domain of Neurospora crassa QA-1F (UniProtKB:P11638). This property can be utilized to form a binary expression system to control the spatial and temporal expression of a gene of interest: a transgene or modified endogenous locus in which the target gene of interest is downstream of QUAS sequences can be combined with a transgene or modified endogenous locus encoding any 'QF driver' that includes the QA-1F DNA-binding domain plus a transcriptional activation sequence (FBrf0210697, reviewed in FBrf0214230, FBrf0233764). The presence of the P\T fragment is expected to result in the QUASp regulatory region being expressed well in the female germline in the presence of an appropriate QF driver, similar to the expression seen for UASp.