1.6kb of sna promoter and cDNA coding region up to amino acid 244 (does not include the sna DNA-binding domain) is fused to sequence encoding amino acids 2 to 93 of the Scer\GAL4 gene (includes the DNA-binding domain). Expression is governed by the twi 2XPE mesodermal enhancer. Three alanine residues separate sna amino acid 244 from Scer\GAL4 amino acid 2.