Fig. 1. Molecular characterization of BOP1 and BOP2. (A) Genomic structure (left) and BOP1 and BOP2 expression in the various mutant alleles compared with wild type (right). Dark-shaded boxes are exons, light-shaded boxes are 5' untranslated regions. Black arrows show translational start sites. Triangles mark the T-DNA insertion sites in the various mutant alleles. 4 x 35S indicates the four 35S enhancers present in the activation-tagging T-DNA. The expression levels of BOP1 and BOP2 in the mutants and wild type were quantified by RT-PCR with 18S ribosomal RNA used as control. The BOP1 expression in bop1-6D was detected with northern blot. (B) Alignment of predicted amino-acid sequences of BOP1, BOP2 and NPR1, with BTB/POZ domains and ankyrin-repeats (ANK) indicated. Identical residues between all three proteins are shaded in black, residues that are identical in at least two sequences are shaded in grey. (C) Phylogenetic interrelationship of all Arabidopsis proteins predicted to contain BTB/POZ domains followed by ANK repeats. The At3g43700 gene contains only the BTB/POZ domain and has been used as an outgroup. Bootstrap support values are indicated.