The GAL80ts entry in FlyBase represents a temperature-sensitive version of the Saccharomyces cerevisiae GAL80 gene ( SGDID:S000004515 ). At the permissive temperature of 18[o]C, GAL80ts protein is functional, acting as a negative regulator of the Saccharomyces cerevisiae GAL4 transcriptional activator, by binding to the GAL4 protein. At restrictive temperatures above 29[o]C, GAL80ts can no longer bind GAL4 and its repressive function is lost (FBrf0168032, adapted from FBrf0233764). GAL80ts can thus be used in combination with shifts in temperature to further refine the expression pattern of a gene of interest expressed using the UAS-GAL4 binary expression system, where a transgene or modified endogenous locus encoding a GAL4-based 'driver' is combined with a second transgene or modified endogenous locus in which the target gene of interest is downstream of UAS sequences. GAL80ts can potentially be used to suppress any binary expression driver or split system hemidriver that contains the interacting C-terminal portion of the GAL4 gene.