Nucleosome positioning While the DNA sequence of most cells of an organism is the same, the binding patterns of transcription factors and the corresponding gene expression patterns are different. To a large extent, differences in transcription factor binding are determined by the chromatin accessibility of their binding sites through histone modification and/or pioneer factors. In particular, it is important to know whether a nucleosome is covering a given genomic binding site or not. This can be determined using a chromatin immunoprecipitation assay.
NuclEosomE PositioNInG wHilE the dna seQUencE oF MOst cElls Of AN orGaniSm iS the SAMe, the bindINg paTterNs of TrANscription factors aND thE correspondinG Gene exprESsIOn patTerNS aRE differENt. to a large exTeNT, DIfferEnceS in tRansCRiptIon Factor biNding aRE DEteRminED by tHE CHROMatiN acCessiBILiTY Of Their bINdinG sitES thRouGh HisTone modIFIcaTION anD/or pionEER faCTorS. IN partIcUlar, it is iMpOrtAnt to know wheTHEr a nUcLeosome is CoveRIng a Given gEnOmiC BIndIng SitE or noT. tHIs CAN be DeTErMineD Using A chroMatin immuNoPRECipItatIoN assay.