In this postgenome era, understanding how a cell regulates access to information encoded in the deoxyribonucleic acid (DNA) is essential. In eukaryotic cells, DNA is bound to histone proteins to form chromatin fibers. Numerous studies have now shown that post-translational histone modifications play an important role in regulating the access of DNA-dependent proteins to the DNA template. Determining the status of histone modifications in a genomic region has proven to yield information on the chromatin structure and the regulation of a specific gene in vivo. Chromatin immunoprecipitation (ChIP) allows researchers to determine the status of both histone modifications and the nuclear effector proteins located at gene of interest. ChIP, if applied globally, can also reveal how chromatin structures are dynamically changed when cells respond to certain stimuli. In this chapter, we describe this powerful technique in detail.
