The GMAT (Genome-wide MAppping Technique) was developed by the combination of ChIP (chromatin immunoprecipitation) and SAGE (serial analysis of gene expression) protocols. Briefly, the chromatin prepared by sonication is subject to immunoprecipitation using specific antibody. DNA from precipitated chromatin is ligated with biotinylated linker and digested with NlaIII restriction enzyme. The DNA fragments with biotinylated linker are isolated and ligated with NlaIII-site specific linker. The DNA is cut with MmeI restriction enzyme to generate 21-base seqeunce tags and ligated each other to form ditags. After removing linkers by NlaIII, isolated ditags are concatenated and determined the sequence. The genomic position of tags is identified by DNA sequences and the detected number of each tag sequence represents the degree of enrichment by means of specific antibody.
