Originally developed in 2009 (Hoshino & Fujii), the locus-specific ChIP technologies enable us to purify specific genomic regions retaining molecular interactions and identify molecules interacting with those regions. Locus-specific ChIP technologies consist of insertional chromatin immunoprecipitation (iChIP) and engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP; Fujita & Fujii, 2013).
In iChIP, specific genomic regions tagged with the recognition sequences of an exogenous DNA-binding protein such as LexA are subjected to affinity purification (Fig. 1). In enChIP, specific genomic regions are tagged with engineered DNA-binding molecules such as TAL proteins and the CRISPR system consisting of a catalytically inactive form of Cas9 (dCas9) plus guide RNA (gRNA) for biochemical purification (Fig. 2).