Nuclear factor NF‐kappa B can interact functionally with its cognate binding site to provide lymphoid‐specific promoter function.

Enhancers and promoters, cis‐acting regulators of mammalian gene expression, are modular units containing multiple short binding sites for specific trans‐acting transcription factors. To investigate if factors binding to enhancer sequences are functionally different from promoter‐binding factors, we asked if a short DNA sequence element in the immunoglobulin kappa (kappa) light chain enhancer that binds to the nuclear factor NF‐kappa B could also serve as a functional promoter element. A synthetic oligonucleotide containing this binding site was placed in either orientation upstream of the beta‐globin TATA‐element. In myeloma cells, the NF‐kappa B binding site efficiently directed transcription. The promoter activity was directly correlated with the presence of the nuclear factor NF‐kappa B: there was no transcription in fibroblasts or in unstimulated pre‐B cells where the factor was absent. Transcription could be stimulated in pre‐B cells by treatments known to activate NF‐kappa B. Thus, the same nuclear factor can act as a positive activator of both enhancer and promoter function, suggesting that the two functions involve similar events in the transcription process.