Transgenic construct used to study the mechanism of action of the gypsy insulator. Contains a reporter composed of the yolk protein fat body enhancer (FBE1) element upstream of the Yp2 promoter and 5' untranslated region fused to the lacZ coding region. Three copies of the third su(Hw) protein binding site of the gypsy insulator have been inserted between the FBE1 element and the Yp2 promoter.