UASt regulatory sequences drive expression of Gcn5 that has been mutated to contain the F304S amino acid replacement (this is equivalent to the F307S mutation in the human Hsap\KAT2B ortholog; F307S is a potentially damaging mutation found to be segregating with the disease phenotype in a family with intellectual disability, microcephaly, cardiomyopathy and steroid-resistant nephrotic syndrome). The coding sequence is tagged at the C-terminal end with Tag:FLAG.