One of the sev enhancers of the progenitor allele is deleted. In what remains, sev amino acids 1865 to 2554, lacking most of the extracellular domain, are encoded by cDNA are under the control of one sev enhancer and Hsp70 promoter. N-terminal signal sequence is provided by an inframe fusion with the signal peptide of Lcp3, and the protein is marked with a Tag:MYC epitope.
Only homozygotes display a rough eye phenotype.