- T3 RNA polymerase is a DNA-dependent RNA polymerase derived from bacteriophage T3, closely related to T7 RNA polymerase, but with its own distinct promoter specificity.
- It recognizes and binds exclusively to the T3 promoter sequence, initiating high-efficiency transcription of downstream genes. Like T7 and SP6 polymerases, T3 is commonly used in in vitro transcription systems due to its simplicity, reliability, and ability to produce large quantities of RNA.
- It functions independently of additional transcription factors and, when provided with a DNA template bearing a T3 promoter, along with ribonucleotides and proper buffer conditions, can rapidly synthesize RNA with high fidelity.
- T3 RNA polymerase is particularly useful in experimental setups where differential expression of multiple genes or strand-specific RNA probes is required. For example, one strand of a DNA template might be cloned under a T3 promoter and the opposite strand under a T7 promoter, enabling the synthesis of sense and antisense RNAs for hybridization or knockdown studies.
- T3 is also used to generate mRNAs for in vitro translation assays, microinjection, and functional RNA studies, especially in systems that benefit from orthogonal promoter usage.
- While less commonly used than T7, T3 polymerase remains a valuable alternative in protocols where its unique promoter specificity or transcriptional behavior offers experimental advantages.
