Protein-binding A + T-rich motifs flank the duck beta A-globin enhancer

The duck beta A-globin (beta GLB) enhancer DNA was analysed by footprinting for sites of specific binding of proteins extracted from duck erythrocytes. The results were compared with previously determined protein binding to the homologous region in chicken DNA. Two A + T-rich protein-binding sites, not recognized in chicken, were found at the 5'-end and the 3'-end of the duck beta GLB enhancer. The 5'-motif (designated BS-1; 5'-AAACAAAATGAA) binds proteins extracted from both embryonic and adult erythrocytes, while the 3'-motif (BS-2; 5'-ATAAACAAGGTC) binds protein from embryonic cells only.