BSAP cis element in exon 1 of human PRDM1 gene. (A) Location of binding sites for transcription factors in a partial sequence of human PRDM1 gene. Theoretic binding sites for the factor are underlined, and the score obtained with the TFMATRIX program for binding site matching is shown. Data for BSAP factor are shaded. (B) Comparison of phylogenetic sequences in exon 1 regions between mammals and avian species. The BSAP consensus-binding site region (shown in bold) was obtained with the TFMATRIX program. The most conserved positions are shaded. Capital and lowercase letters show nucleotides matching or not matching the theoretic BSAP-binding site, respectively. Note that chicken sequence lacks 4 essential positions against 2 lacking in mammals.