The cymTA entry in FlyBase represents an artificial transcriptional activator ('driver') that includes the DNA-binding domain from the cymR gene of Pseudomonas putida and a transcriptional activation domain from the Herpes simplex virus Type 1 VP16 gene. The cymR DNA-binding domain binds specifically to the cymO DNA sequence, and thus cymO and cymTA 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 cymO sequences is combined with a second transgene or modified endogenous locus encoding the cymTA driver. The activity of the cymTA driver can potentially be suppressed by cumate (a specific ligand of cymR): upon binding to cumate it is expected that cymTA will undergo a conformational change preventing it from binding the cymO sequence, thus reducing or preventing its ability to induce transcription (PMID:17083727). The exact sequence of the driver may differ depending on the particular transgene or modified endogenous locus being used. In particular, the number of VP16 activation domains present may vary, and/or the VP16 activation domains may contain mutations that alter the strength of transcriptional activation.