BANC-seq to identify genome-wide transcription factor binding affinities to native chromatin

BANC-seq (Binding Affinities to Native Chromatin by sequencing) allows determination of absolute apparent binding affinites of transcription factors to native chromatin in a genome-wide manner. In this study, we establish the method and show that chromatin and DNA sequence define binding affinites of FOXA1, SP1, YY1 and MYC/MAX complex. To relate the identified binding affinities to the actual transcriptional levels of these transcription factors in the cells used in this study, and to confirm that the nuclear isolation protocol used in the study does not lead to loss of nuclear proteins, we have generated whole proteomes including proteomics standards for absolute quantification of proteins. In addition, to validate some of the findings of the study, we have performed PAQMAN (Protein-nucleic acid affinity quantification by MAss spectrometry in nuclear extracts), as well as DNA pulldowns followed by mass spec.