EBF interacts with 5 independent binding sites in the promoter of the human surrogate light chain 14.1.

(A) Sequence alignment between the human 14.1 and mouseλ5 promoters. Conserved sequence is indicated by − and insertions/deletions by *. Potential EBF sites in the14.1 promoter as well as the experimentally confirmed EBF-binding sites in the λ5 promoter42 are aligned to a consensus EBF-binding site. Overlining indicates the oligonucleotides used in the EMSA analysis in panel B. E-boxes (CANNTG) in either the 14.1 or λ5 promoter are indicated by text and underlining. (B) EMSA obtained by competition for binding by hEBF to an excess of mb-1 promoter EBF site by the addition of increasing amounts of PCR-amplified 14.1promoter or duplex oligonucleotides spanning potential EBF-binding sites in the 14.1 promoter, as indicated. A duplex oligonucleotide spanning the EBF-binding site from the humanmb-1 promoter was used as positive control, and a BSAP-binding site from the human CD19 promoter as negative control. The gels have been cut.