Abstract
The proteins interaction with DNA is one of the key regulatory elements of many biological processes; including gene transcription, epigenetic modification or cell differentiation. Immunoprecipitation of chromatin; ChIP; is a method used to assess the interaction of the protein with a DNA sequence, and determines the localization of specific locus in the genome. The main steps of this method are fixation, sonication, immunoprecipitation and analysis of DNA. Although the immunoprecipitation assay is a multipurpose tool applied in biochemistry and biotechnology, it requires optimization. This paper describes several critical parameters that should be taken into account when immunoprecipitation assay is applied.