Nuclear factors binding to the human immunoglobulin heavy-chain gene enhancer

The human immunoglobulin heavy chain (IgH) gene contains at least two tissue-specific regulatory regions, which are similar to the mouse IgH gene. One is the J-C enhancer and another is located in the 5' promoter region. Using an electrophoretic mobility shift assay and DNase I footprint, we have examined the interaction of factors in B cell nuclear extracts with the two regulatory regions of the human IgH gene. We have identified a nuclear factor in mouse B cell nuclear extracts which bound to specific sequence in the human IgH enhancer. This factor is apparently not present in mouse fibroblast nuclear extracts. We also found factor(s) which bound to the highly conserved octanucleotide sequence within the human IgH enhancer and 5' promoter regions.