What is ChIP?

 ChIP is a technique used to study the association of specific proteins, or their modified isoforms, with defined genomic regions. It is a fast growing research technique and is commonly used for mapping the DNA-protein interactions in cells which are crucial for correct gene regulation. For example, they may be used to determine whether proteins such as transcription factors and modified histones bind to a particular region of DNA of living cells or tissues.

In a ChIP assay, fragments of the DNA-protein complex (chromatin) are cross-linked in such a way so as to retain the specific DNA-protein interactions. The chromatin is then extracted and sheared either by sonication or enzymatic digestion into small fragments. The DNA/protein fragments are selectively immunoprecipitated using antibodies directed against the protein of interest and the resulting fractions treated to separate the DNA and protein components.