T7 RNA polymerase

T7 RNA polymerase is a polymerase expressed by Escherichia coli from the RNA polymerase gene of T7 bacteriophage. T7 RNA polymerase is highly specific and involved in in vitro transcription (IVT) of mRNA. In the presence of Mg2+, T7 RNA polymerase only uses the single-stranded or double-stranded DNA containing the T7 promoter sequence as a template, and uses NTP as a substrate to synthesize RNA complementary to the single-stranded DNA downstream of the promoter[1][2].