Figure 1.

The LS4 sequence contributes to scs’ insulator activity. (A) Schematic of the mini-w reporter gene (white rectangle; bent arrow: TSS), showing the location of 5′ test sequences and the 3′ scs insulator. The upstream and downstream P-element sequences are not shown. (B) Assay results for each sequence tested in the 5′ insulator location, given as percent of fly lines with yellow/orange (Y/O) or dark-orange/light-red/red (DO/LR/R) eyes. Also indicated are the number of fly lines scored. Values in green indicate a functional insulator; in blue indicate impaired insulator activity; in black indicate a nonfunctional insulator. On the left are schematics of the scs’ sequences tested. Arrowheads represent CGATA motifs, stars represent mutated motifs, and H and L indicate the high and low affinity BEAF binding sites. Bent arrows represent TSSs. Open and filled rectangles roughly represent nuclease sensitive and resistant regions, respectively (Udvardy et al. 1985). Dotted lines indicate regions of scs’ present in M, S, and X monomers. Red boxes indicate the linker-scanning mutations present in LS1–LS6, which were tested as dimers. All constructs had a 3′ scs insulator except: a: no 3′ scs; b: data from Cuvier et al. (1998);. c: includes 18 fly lines from Cuvier et al. (1998); d: includes 10 fly lines from Cuvier et al. (1998).