Determination of Histone Acetylation Status by Chromatin Immunoprecipitation

Histone acetylation is the most studied posttranslation modification of nucleosomes. Understanding the mechanisms involved in global and promoter-specific histone acetylation will shed light on the control of transcriptional regulation. Chromatin immunoprecipitation is a powerful technique to study protein–DNA interactions in vivo. Proteins and DNA are cross-linked with formaldehyde, cells are lysed, and DNA is sheared by sonication. Protein–DNA complexes are immunoprecipitated with antibodies specific for total and acetylated histones and the relative occupancy of acetylated and total histones at selected loci is assessed by real-time PCR of the purified DNA.