Top : Molecular Biology : Protein : Immunoprecipitation (IP) : Chromatin Immunoprecipitation (ChIP Assay)

Summary: Chromatin immunoprecipitation (ChIP) is a powerful tool for identifying proteins, including histone proteins and non-histone proteins, associated with specific regions of the genome by using specific antibodies that recognize a specific protein or a specific modification of a protein. The initial step of ChIP is the cross-linking of protein-protein and protein-DNA in live cells with formaldehyde. After cross-linking, the cells are lysed and crude extracts are sonicated to shear the DNA. Proteins together with cross-linked DNA are subsequently immunoprecipitated. Protein-DNA cross-links in the immunoprecipitated material are then reversed and the DNA fragments are purified and PCR amplified. There are two general types of ChIP experiments: Cross-linking ChIP (X-ChIP or XChIP) which uses chromatin fixed with formaldehyde and fragmented by sonication and native chromatin ChIP (N-ChIP or NChIP) which uses native chromatin prepared by nuclease digestion of cell nuclei.
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