FIG. 3.
Axin2 promoter and intron 1 sequences contain potential Tcf/LEF binding sites within longer conserved DNA sequences. (A) A 5.6-kb DNA fragment containing the Axin2 promoter, exon 1, intron 1, and part of exon 2 was subcloned from a mouse BAC clone and sequenced. Exons are shown as gray boxes, and the sequence is numbered with bp 1 corresponding to the start of the cDNA sequence. Eight conserved Tcf/LEF binding sites (underlined and designated T1 to T8) were identified. The site-directed mutations introduced into each site (Fig. 5) are shown on top of the original sequence. (B) Conservation of five potential Tcf/LEF binding sites and surrounding sequences between human and mouse Axin2 promoter/intron 1 sequences. Sequence comparison between mouse and human BAC clones revealed strong conservation of sites T2, T3, T4, T5, and T8, as well as between 106 and 151 bp of the surrounding DNA sequence. The conserved sequences are as follows: T2, −128 to −3; T3, 262 to 412; T4 and T5, 701 to 806; and T8, 2534 to 2646.