The lexA::p65::GAD entry in FlyBase represents an artificial transcriptional activator ('driver') that includes the DNA-binding domain from the Escherichia coli lexA gene (ECOGENE:EG10533) and two transcriptional activation domains; one from the Homo sapiens 'p65' gene (RELA, HGNC:9955) and the other from the Saccharomyces cerevisiae GAL4 gene ( SGDID:S000006169 ). In Escherichia coli the lexA protein acts as a transcriptional repressor, binding specifically to the lexAop DNA sequence via its DNA-binding domain (reviewed in PMID:18726173). By fusing the lexA DNA-binding domain to the transcriptional activation domains, the resulting lexA::p65::GAD protein is converted into a transcriptional activator that specifically binds lexAop. lexAop and lexA::p65::GAD thus 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 lexAop sequences is combined with a second transgene or modified endogenous locus encoding the lexA::p65::GAD driver. The presence of two transcriptional activation domains is expected to enhance the activity of the driver (FBrf0247844). The exact sequence of the driver may differ depending on the particular transgene or modified endogenous locus being used.