T3 RNA Polymerase is a member of the DNA-dependent RNA polymerase family and was originally isolated from Bacteriophage T3. It is highly specific to the T3 promoter and will only transcribe from DNA templates with that promoter. Commercially produced T3 RNA Pol enzyme is expressed from E. coli and is active at 37°C. It is recommended for RNA synthesis applications such for generating in vitro translation templates, hybridization probes, RNA assay substrates, and others.