Editing Reverse transcriptase (section)

{{Short description|Enzyme which generates DNA}}
{{Infobox protein family
| Symbol = RVT_1
| Name = Reverse transcriptase<br />(RNA-dependent DNA polymerase)
| image = Reverse transcriptase 3KLF labels.png
| width =
| caption = Crystallographic structure of [[HIV]]-1 reverse transcriptase where the two subunits p51 and p66 are colored and the active sites of polymerase and nuclease are highlighted.<ref name="pmid20852643">{{PDB|3KLF}}; {{cite journal | vauthors = Tu X, Das K, Han Q, Bauman JD, Clark AD, Hou X, Frenkel YV, Gaffney BL, Jones RA, Boyer PL, Hughes SH, Sarafianos SG, Arnold E | title = Structural basis of HIV-1 resistance to AZT by excision | journal = Nature Structural & Molecular Biology | volume = 17 | issue = 10 | pages = 1202–9 | date = October 2010 | pmid = 20852643 | pmc = 2987654 | doi = 10.1038/nsmb.1908 }}</ref>
| Pfam = PF00078
| Pfam_clan = CL0027
| InterPro = IPR000477
| SMART =
| PROSITE = PS50878
| SCOP = 1hmv
| TCDB =
| OPM family =
| OPM protein =
| CDD = cd00304
}}
{{infobox enzyme
| Name       = RNA-directed DNA polymerase
| EC_number  = 2.7.7.49
| CAS_number = 9068-38-6
| GO_code    = 0003964
| image      =
| width      =
| caption    = 
}}

A '''reverse transcriptase''' ('''RT''') is an [[enzyme]] used to convert [[RNA genome]] to [[DNA]], a process termed '''reverse transcription'''. Reverse transcriptases are used by [[virus]]es such as [[HIV]] and [[hepatitis B virus|hepatitis B]] to replicate their genomes, by  [[retrotransposon]] mobile genetic elements to proliferate within the host genome, and by [[eukaryote|eukaryotic]] cells to extend the [[telomeres]] at the ends of their [[Chromosome#Eukaryotes|linear chromosomes]]. The process does not violate the flows of genetic information as described by the classical [[central dogma of molecular biology|central dogma]], but rather expands it to include transfers of information from RNA to DNA.<ref name = "Crick_1970">{{cite journal | vauthors = Crick F | title = Central dogma of molecular biology | journal = Nature | volume = 227 | issue = 5258 | pages = 561–3 | date = August 1970 | pmid = 4913914 | doi = 10.1038/227561a0 | s2cid = 4164029 | bibcode = 1970Natur.227..561C }}</ref><ref>{{cite book | vauthors = Sarkar S |title=The Philosophy and History of Molecular Biology: New Perspectives |date=1996 |publisher=Kluwer Academic Publishers |location=Dordrecht |pages=187–232}}</ref><ref>{{cite journal | vauthors = Danchin É, Pocheville A, Rey O, Pujol B, Blanchet S |title=Epigenetically facilitated mutational assimilation: epigenetics as a hub within the inclusive evolutionary synthesis |journal=Biological Reviews |date=2019 |volume=94 |issue=1 |pages=259–282 |doi=10.1111/brv.12453 |pmc=6378602|s2cid=67861162 |doi-access=free }}</ref>

Retroviral RT has three sequential biochemical activities: RNA-dependent [[DNA polymerase]] activity, [[ribonuclease H]] (RNase H), and DNA-dependent DNA polymerase activity. Collectively, these activities enable the enzyme to convert single-stranded RNA into double-stranded cDNA. In retroviruses and retrotransposons, this cDNA can then integrate into the host genome, from which new RNA copies can be made via host-cell [[transcription (biology)|transcription]]. 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 [[DNA microarray|genome analysis]].