Figure 1. The process of CATCH.

The flowchart demonstrates philosophical basis of CATCH. It shows that a cell population is first formaldehyde-fixed to capture DNA–protein–DNA interaction. The DNA is then sheared into small fragments using sonication. The resulting fragmented DNA–protein–DNA complexes are hybridized to a biotinylated oligo in order to enrich for a region of interest. While the targeted sequence is pulled out of the entire DNA population using streptavidin-linked magnetic beads, any associated protein–DNA complexes are also enriched. Subsequent de-crosslinking and PCR amplify the target sequence and any (potentially) associated sequences. Next-generation sequencing allows the identification of any DNA sequences physically associated with the locus (via proteins) to which the biotinylated probe was originally hybridized.