ATAC-seq is a molecular biology technique used to identify regions of open chromatin in DNA. It utilizes transposase Tn5, which binds and cuts regions of open chromatin. These regions are then isolated, amplified, and sequenced. Peak calling (using algorithms such as F-seq) is used to determine the enrichment of open chromatin regions from sequencing data. These regions are likely binding sites of gene regulatory proteins, such as transcription factors.
This painting depicts inaccessible, tightly-wound chromatin in water, enrichment of clipped genomic segments (open chromatin regions) as peak signal in mountains, and Tn5 transposase as clouds.