Distinction between AP1 and NF-E2 factor-binding at specific chromatin regions in mammalian cells.

Specific nuclear factor-DNA complexes formed within the promoters and enhancers are essential for transcriptional regulation. For eukaryotic systems, however, some DNA motif(s) are capable of binding to a family of related factors, thus making it difficult to identify the factor actually binding on the chromatic DNA in vivo and modulating the local transcription processes. To resolve this matter, we have refined a chromatin immunoprecipitation assay. Using the assay, we could directly link the regulatory functions of two members of the AP1/NF-E2 transcription factor family and their stable binding in vivo within distinct chromatin regions. The study demonstrated the feasibility of a general scheme in the determination of the identity of specific factor(s), among a group of family members, bound at unique sequence(s) in living mammalian cells.