The GAL4::QF entry in FlyBase represents an artificial transcriptional activator ('driver') that includes the DNA-binding domain from the Saccharomyces cerevisiae GAL4 gene ( SGDID:S000006169 ) and a transcriptional activation domain of Neurospora crassa QA-1F (UniProtKB:P11638). The GAL4 DNA-binding domain binds specifically to the UAS DNA sequence and thus UAS and GAL4::QF form a binary expression system that can be used to control the spatial and temporal expression of a gene of interest: a transgene or modified endogenous locus carrying the target gene of interest downstream of UAS sequences is combined with a second transgene or modified endogenous locus encoding the GAL4::QF driver. The exact sequence of the driver may differ depending on the particular transgene or modified endogenous locus being used. For example, the extent of GAL4 sequence present may vary such that in some cases the middle domain may be present in addition to the DNA-binding domain, or the QA-1F activation domain may contain mutation(s) that alter its activity, changing the strength of an individual driver. Since the GAL4::QF driver includes the QA-1F activation domain targeted by the QS repressor, it can be suppressed by QS (FBrf0227669).