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Fig. 3. PTS facilitates and restricts enhancer activity to a single promoter.
Constructs W32 and W81 were tested. The former contains an FRT flanked PTS and
Fab-8, and the IAB8 enhancer, where as the latter contains FRT
flanked PTS and suHw, plus a 1.0 kb IAB5 enhancer. Large orange
arrowheads indicate FRT sites. (A,B) A representative line exhibiting a
selective IAB8-w interaction is shown. (C,D) The same strain after
removal of the Fab-8 insulator and the PTS by Flp-mediated
recombination (Golic and Lindquist,
1989). There is a severe reduction of IAB8-w interaction
with the accompanying activation of lacZ. (E,F) Most transgenic
strains carrying the W81 display an IAB5-lacZ interaction as shown
here. (G,H) The same strain after Flp-FRT analysis. Note the reduction of
IAB5-lacZ interaction and the concomitant appearance of
IAB5-w interaction.