This unit describes Assay for Transposase-Accessible Chromatin with 
high-throughput sequencing (ATAC-seq), a method for mapping chromatin 
accessibility genome-wide. This method probes DNA accessibility with hyperactive 
Tn5 transposase, which inserts sequencing adapters into accessible regions of 
chromatin. Sequencing reads can then be used to infer regions of increased 
accessibility, as well as to map regions of transcription-factor binding and 
nucleosome position. The method is a fast and sensitive alternative to DNase-seq 
for assaying chromatin accessibility genome-wide, or to MNase-seq for assaying 
nucleosome positions in accessible regions of the genome.