Chromatin immunoprecipitation in mammalian cells.

The ensemble of the genes in the mammalian genome is organized into a structure of DNA and proteins known as chromatin. The control of gene expression by the proteins that bind to chromatin regulates many cell processes, such as differentiation and proliferation. Transcription of protein-encoding genes in mammalian cells is performed by the concerted action of the RNA polymerase II holoenzyme, transcription factors, co-activator complexes that bind to the promoter areas of genes. In addition, different proteins can interact with these complexes and chromatin to create a repressive state. In order to fundamentally understand transcriptional control, it is important to define the areas that these proteins will bind. Classical laboratory techniques unable to provide distinct locations of these factors have now been replaced by the chromatin immunoprecipitation (ChIP) assay. The ChIP technique allows us to isolate chromatin along with its associated proteins from cells and analyse the binding sites of specific proteins and complexes at high resolution.