Fig. 1

Organization of the bithorax complex and functional dissection of the Insv protein: DNA binding and multimerization. a Map of the Abd-B region of the bithorax complex. The relative location of the Abd-B regulatory domains, iab-5, iab-6, iab-7, and iab-8, and the positions of the boundary elements, Mcp, Fab-6, Fab-7, and Fab-8, and the Abd-B transcription unit. Map of the Fab-7 nuclease hypersensitive sites, HS*, HS1, HS2, and HS3 (iab-7 PRE), and location of the binding sites for the GAGA factor and Insv. Probes for EMSA experiments P3, P2, and 2xPal. P3 is a 32-bp sequence derived from distal side of HS1 (dHS1). Position of the CCAATTGG palindrome is indicated by red box. P2 is a 117-bp sequence derived from the proximal side of HS1. On the right end it contains the Elba sequence CCAATAAG (blue box) and a binding site for the GAGA factor (orange oval). 2xPal is a 122-bp artificial sequence containing two CCAATTGG palindromes. b Full-length and various truncated versions of the Insv protein are expressed in bacteria and then tested for DNA-binding activity. Schematic diagram of the Insv proteins tested for DNA-binding activity. The bacterially expressed proteins were tagged with either GST (G) or His-Sumo (HS). DNA-binding activity is indicated by (+) or (−). c EMSA of probe P3 by GST-tagged full-length and truncated Insv proteins. d EMSA of C-BEN and BEN proteins (see diagram in b) tagged with GST (G) or His-Sumo (HS). Amount of protein added (left to right) to the reaction mix was estimated based on the relative intensity of the Coomassie-stained protein bands in SDS-PAGE gels: 0.169 μm, 0.085 μm, and 0.042 μm