The GFP-CP190dZnF and the Cp190ΔM proteins are fully functional in the gypsy insulator. (A) The gypsy insulator-dependent wing phenotype of the ct6mutation in the indicated genetic backgrounds. Wings of the ct6flies have a cut shape and lack of margin bristles (top left). The two doted lines mark the veins L3 and L5 between which the margin bristles are not developed at all. The ct6; CP190H4-1 wing has some margin bristles between L3 and L5, and is rounder in shape (middle left). The wing shape of the CP190 deficient CP1903/CP190P1flies is restored to a ct+-like shape with fully developed margin bristles (bottom left), indicated. A copy of the P[Ubi63e::mRFP-CP190] (top right), P[Ubi63e::GFP-CP190dZnF] (middle right) or the P[CP190ΔM] (bottom right) transgene rescues the defective gypsy insulator function in the CP190 deficient CP1903/CP190P1background. The rescued flies have the cut wing shape similar to the ct6; CP190+flies. (B) Localization of the mutated Cp190 proteins to the gypsy insulator insertion at the y locus on the y2polytene chromosome. Shown are the tips of X chromosomes. The y locus that contains a copy of the gypsy insulator is indicated by white arrows. Distribution of the GFP-CP190dZnF protein (middle panel) and the Cp190ΔM protein (bottom panel) on the polytene chromosomes of the indicated flies was revealed by anti-Cp190 (left column). The anti-Mod(mdg4)67.2 (middle column) shows the distribution of the Su(Hw) insulator complex. The right column shows the merged images of the left and the middle columns.