Fig. 2. Putative transcription factor binding sites in highly conserved homology regions H1 and H2 that are part of the -58/-56 kb enhancer. (A,B) Only those homology sequences were analyzed that contributed to enhancer activity in a previous study (Buchberger et al., 2003). The consensus sequences marked by gray shaded boxes were designated according to the prediction obtained by Transfac database. Homeo (TAATT) and paired (GTAACT) domain motifs within the putative Xvent2 site were also predicted by the Transfac program. Binding sites highlighted in dark gray were functionally tested by site-directed mutagenesis of the underlined sequences in the complete -58/-56 kb enhancer. Individual nucleotide exchanges are indicated.