![]() ![]() Like DNA and RNA polymerases, reverse transcriptase helps in the synthesis of polynucleotide chains in 5’ to 3’ direction. Just like the Klenow fragment structure the α subunit has three components namely finger, palm and thumb. Reverse transcriptase is made up of two subunits α and β, hence it is a heterodimer, with α subunit having a molecular weight of 65kDa and the βsubunit having a molecular weight of 90kDa. Most of the viruses that are the cause of infection in animals and other organisms will contain RNA-dependent DNA polymerase which is also known as Reverse transcriptase. Various infection processes like cell lysis and integration into the host genome or remaining dormant are caused by the DNA duplex generated. Hybridization of the primer binding site of the second strand takes place with the primer binding site of the first strand at the complementary sequences.Įnzyme integrase incorporates the extended strands into the host genome. In the next step extension of the first strand of complementary DNA take place and there is a degradation of RNA takes place by RNase H. Once the U5 and R regions are degraded the primer jumps to the 3’ end of viral RNA and now the cDNA which is newly synthesized. RNase H which is a domain found on the reverse transcriptase enzyme helps in the degradation and subsequent removal of the 5’ U5 and R regions of the RNA. In the next step the complementary DNA binds to a non-coding region which is known as U5 region and at the same time to a direct repeat which occurs at both the ends of RNA molecule and this region is known as the R- region. The process of reverse transcription in viruses involves the following step −įirst Transfer RNA which is cell-specific acts as a primer and anneals itself to the complementary part of the viral genome and this part is known as the primer binding site (PBS). With all these processes one more process takes place in viruses where genetic material is RNA, in such organisms a complementary DNA (cDNA) is formed from a template RNA by an enzyme called reverse transcriptase. The third process involves the translation of messages on RNA to a polypeptide chain with a particular amino acid in the ribosomes. ![]() The second process is transcription, which is the process by which a genetic message present in the DNA is copied into an RNA. The first process is replication, the copying of parental DNA to form daughter DNA molecules with identical nucleotide sequences. USA 80, 1830–4.The central dogma of molecular biology stated the utilization of genetic information. et al., eds., John Wiley and Sons, New York, NY. (1987) In: Current Protocols in Molecular Biology, Ausubel, F.M. Ĭhoose Your Configuration: Learn more about our custom options for this product at: References The DNA-dependent DNA polymerase is provided with 10X Reaction Buffer. The 3´→5´ exonuclease activity can be used to generate blunt ends from a 3´-overhang. The 5´→3´ polymerase activity of Klenow Fragment can be used to fill in 5´-protruding ends with unlabeled or labeled dNTPs, to sequence single- or double-stranded DNA templates, for in vitro mutagenesis using synthetic oligonucleotides, for cDNA second-strand synthesis and to generate single-stranded DNA probes. coli DNA Polymerase I that lacks the 5´→3´ exonuclease activity of intact DNA polymerase I but retains its 5´→3´ polymerase, 3´→5´ exonuclease and strand displacement activities. DNA Polymerase I Large (Klenow) Fragment is a 68kDa C-terminal fragment of E. ![]()
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