The Chromatin immunoprecipitation (ChIP) assay is a technique used to investigate the interaction between proteins and DNA in the cell.     
The Chromatin immunoprecipitation (ChIP) assay is a technique used to investigate the interaction between proteins and DNA in the cell. For example, it may be used to determine whether proteins such as transcription factors and modified histones bind to a particular region on the endogenous chromatin of living cells or tissues.     
     
In a ChIP assay, fragments of the DNA-protein complex (i.e. chromatin) are prepared in such a way so as to retain the specific DNA-protein interactions. These fragments are captured on an in inert porous solid phase disc using an immobilized antibody specific for the protein present in the complex. The isolated chromatin fraction can then be cleaned up, released into fresh buffers and treated to separate the DNA and protein components. The identity of DNA fragments isolated in connection with a particular protein can then be determined by Polymerase Chain Reaction (PCR), Real Time PCR, hybridization on microarrays, direct sequencing or other technologies used for identification of DNA fragments.