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The Reverse Transcriptase (RT) is an enzyme capable of catalyzing the synthesis of DNA from a single strain of RNA or DNA ([[Literature:3941|Baltimore 1970]]; [[Literature:76318|Temin and Mizutani 1970]]). This enzyme has been associated with Telomerase Reverse Transcriptases (TERTs) involved in the replication of the ends of eukaryotic organisms’ chromosomes ([[Literature:53530|see review Nakamura and Cech 1998]]).

The reverse-transcription process is common among a wide range of prokaryotic and eukaryotic mobile genetic elements, and requires a primer of 12-18 bases in length usually provided by the 3´end of a host tRNA ([[Literature:20033|Eickbush 1994]]). As an evolutionary relationship is commonly assumed to exist among all RT-dependent mobile genetic elements, they have been collectively termed Retroelements ([[Literature:76300|Temin 1989]]).

At the primary structure level, RTs codified by ''Ty3/Gypsy'' and ''Retroviridae'' elements expand approximately 350 residues of the pol polyprotein, including an alignable core of approximately 180 aa wherein seven conserved regions can be distinguished ([[Literature:83966|Xiong and Eickbush 1988]]; [[Literature:83963|1990]]).

At the three-dimensional (3D) structure level the RT codified by the HIV-1 retrovirus is an asymmetrical heterodimer composed of two subunits of 66 and 51 kDa, p66 and p51 respectively. P66 can be divided into five structural subdomains consisting in the [[Ribonuclease H|RNaseH]] domain and four subdomains which, due to their similarity to a human right hand, are referred to as fingers, palm, thumb, and connection ([[Literature:39082|Kohlstaedt ''et al.'' 1992]]). P51 is a p-66´ derivative after proteolytic processing and excision of the RNase H ([[Literature:16175|Di Marzo ''et al''. 1986]]; [[Literature:83412|Wondrak ''et al''. 1986]]; [[Literature:43884|Lightfoote ''et al.'' 1986]]).

Although several evidences indicate that RTs encoded by other vertebrate retroviruses also form a heterodimer, the RT may also be functionally active as a monomer (see [[Literature:50655|Misra, Pandey and Pandey 1998]]).

[[Image:ty3gypsy_rt_1.gif|center]]
<center>HIV-1 RT 3D structures adapted from PDB-file [http://www.ebi.ac.uk/pdbsum/1BQM 1BQM]</center>

[[Category:Retroelements]]

Reverse Transcriptase - Revision history

imported>Gydbwiki at 11:11, 22 April 2010