IPTG (syn: Isopropyl β-D-1-thiogalactopyranoside) is a compound that induces transcription of the lac operon by mimicking allolactose, a lactose metabolite. IPTG is routinely used as a tool in cloning and gene recombination to confirm successful gene insertion. It is used with X-Gal or Gluo-Gal in chromogenic substrate in blue-white selection of recombinant bacterial colonies that induce expression of the lac operon in E. coli.
IPTG is soluble in water.
