Long terminal repeat

Identical LTR sequences at either end of a retrotransposon.

A long terminal repeat (LTR) is a pair of identical sequences of DNA, several hundred base pairs long, which occur in eukaryotic genomes on either end of a series of genes or pseudogenes that form a retrotransposon or an endogenous retrovirus or a retroviral provirus. All retroviral genomes are flanked by LTRs, while there are some retrotransposons without LTRs. Typically, an element flanked by a pair of LTRs will encode a reverse transcriptase and an integrase, allowing the element to be copied and inserted at a different location of the genome. Copies of such an LTR-flanked element can often be found hundreds or thousands of times in a genome. LTR retrotransposons comprise about 8% of the human genome.^[1]

The first LTR sequences were found by A.P. Czernilofsky and J. Shine in 1977 and 1980.^[2]^[3]

^ Ishak, Charles A.; De Carvalho, Daniel D. (2020). "Reactivation of Endogenous Retroelements in Cancer Development and Therapy". Annual Review of Cancer Biology. 4: 159–176. doi:10.1146/annurev-cancerbio-030419-033525.
^ Shine, J.; Czernilofsky, A. P.; Friedrich, R.; Bishop, J. M.; Goodman, H. M. (1977). "Nucleotide sequence at the 5' terminus of the avian sarcoma virus genome". Proceedings of the National Academy of Sciences. 74 (4): 1473–7. Bibcode:1977PNAS...74.1473S. doi:10.1073/pnas.74.4.1473. PMC 430805. PMID 67601.
^ Czernilofsky, A.P.; Delorbe, W.; Swanstrom, R.; Varmus, H.E.; Bishop, J.M.; Tischer, E.; Goodman, H.M. (1980). "The nucleotide sequence of an untranslated but conserved domain at the 3′ end of the avian sarcoma virus genome". Nucleic Acids Research. 8 (13): 2967–84. doi:10.1093/nar/8.13.2967. PMC 324138. PMID 6253899.

[1] Ishak, Charles A.; De Carvalho, Daniel D. (2020). "Reactivation of Endogenous Retroelements in Cancer Development and Therapy". Annual Review of Cancer Biology. 4: 159–176. doi:10.1146/annurev-cancerbio-030419-033525.

[Shine1977-2] Shine, J.; Czernilofsky, A. P.; Friedrich, R.; Bishop, J. M.; Goodman, H. M. (1977). "Nucleotide sequence at the 5' terminus of the avian sarcoma virus genome". Proceedings of the National Academy of Sciences. 74 (4): 1473–7. Bibcode:1977PNAS...74.1473S. doi:10.1073/pnas.74.4.1473. PMC 430805. PMID 67601.

[Czernilofsky1980-3] Czernilofsky, A.P.; Delorbe, W.; Swanstrom, R.; Varmus, H.E.; Bishop, J.M.; Tischer, E.; Goodman, H.M. (1980). "The nucleotide sequence of an untranslated but conserved domain at the 3′ end of the avian sarcoma virus genome". Nucleic Acids Research. 8 (13): 2967–84. doi:10.1093/nar/8.13.2967. PMC 324138. PMID 6253899.

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