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A Reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed ''reverse transcription''. It is mainly associated with retroviruses. However, non-retroviruses also use RT (for example, the hepatitis B virus, a member of the Hepadnaviridae, which are dsDNA-RT viruses, while retroviruses are ssRNA viruses). RT inhibitors are widely used as antiretroviral drugs. RT activities are also associated with the replication of chromosome ends (telomerase) and some mobile genetic elements (retrotransposons). Retroviral RT has three sequential biochemical activities: *(a) RNA-dependent DNA polymerase activity, *(b) ribonuclease H, and *(c) DNA-dependent DNA polymerase activity. These activities are used by the retrovirus to convert single-stranded genomic RNA into double-stranded cDNA which can integrate into the host genome, potentially generating a long-term infection that can be very difficult to eradicate. The same sequence of reactions is widely used in the laboratory to convert RNA to DNA for use in molecular cloning, RNA sequencing, polymerase chain reaction (PCR), or genome analysis. Well studied reverse transcriptases include: * HIV-1 reverse transcriptase from human immunodeficiency virus type 1 () has two subunits, which have respective molecular weights of 66 and 51 kilodaltons.〔http://www.craiklab.ucsf.edu/docs/pub47.pdf Immunologic and Proteolytic Analysis of HIV-1 Structure, University of California, 1989〕 * M-MLV reverse transcriptase from the Moloney murine leukemia virus is a single 75 kDa monomer. * AMV reverse transcriptase from the avian myeloblastosis virus like HIV also has two subunits, a 63kDa subunit and a 95kDa subunit.〔 * Telomerase reverse transcriptase that maintains the telomeres of eukaryotic chromosomes == History == Reverse transcriptases were discovered by Howard Temin at the University of Wisconsin–Madison in RSV virions, and independently isolated by David Baltimore in 1970 at MIT from two RNA tumour viruses: R-MLV and again RSV. For their achievements, both shared the 1975 Nobel Prize in Physiology or Medicine (with Renato Dulbecco). The idea of reverse transcription was very unpopular at first as it contradicted the central dogma of molecular biology which states that DNA is transcribed into RNA which is then translated into proteins. However, in 1970 when the scientists Howard Temin and David Baltimore both independently discovered the enzyme responsible for reverse transcription, named reverse transcriptase, the possibility that genetic information could be passed on in this manner was finally accepted. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reverse transcriptase」の詳細全文を読む スポンサード リンク
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