Bipartite structure of the proximal promoter of a human H4 histone gene

The proximal promoter of the human H4 histone gene FO108 contains two regions of in vivo protein‐DNA interaction, Sites I and II. Electrophoretic mobility shift assays using a radiolabeled DNA probe revealed that several proteins present in HeLa cell nuclear extracts bound specifically to Site I (nt‐125 to nt‐86). The most prominent complex, designated HiNF‐C, and a complex of greater mobility, HiNF‐C′, were specifically compatable by an Sp1 consensus oligonucleotide. Fractionation of HiNF‐C using wheat germ agglutinin affinity chromatography suggested that, like Sp1, HiNF‐C contains N‐acetylglucosamine moieties. Two minor complexes of even greater mobility, designated HiNF‐E and F, were compatable by ATF consensus oligonucleotides. A DNA probe carrying a site‐specific mutation in the distal portion of Site I failed to bind HiNF‐E, indicating that this protein associated specifically to this region. UV cross‐linking analysis showed that several proteins of different molecular weights interact specifically with Site I. These data indicate that Site I possesses a bipartite structure and that multiple proteins present in HeLa cell nuclear extracts specifically with Site I sequences.