Reverse transcriptase is an enzyme used by all retroviruses that
transcribes the genetic information from the virus from RNA into
DNA, which can integrate into the host genome. Usually,
transcription only runs from DNA to RNA, catalyzed by RNA
polymerase. An example of this kind of enzyme is the reverse
transcriptase from the human immunodeficiency virus type 1 (PDB
1HMV, EC 188.8.131.52). Reverse transcriptase is commonly used
in the field of research to be able to apply the Polymerase
chain reaction technique to RNA. The classical PCR technique can
only be applied to DNA strands, but with the help of reverse
transcriptase, RNA can be transcribed into DNA making PCR
analysis of RNA molecules possible. The technique is
collectively called: Reverse Transcriptase Polymerase Chain
Reaction (RT-PCR).