Long terminal repeat
An LTR ( long terminal repeat ) is a 200-3000 bp long DNA repeat unit , which flank genes called LTR elements on both sides and enable them to reintegrate into the genome ( transposition ) after they have been cut out . In retroviruses, there are LTRs at both ends of the genome, which mediate subsequent integration into the provirus .
construction
LTRs contain all signal sequences that are necessary to control gene expression from 5 'to 3':
- Section U3 ( unique 3 ') with GRE (characteristic base sequence TGTTA), enhancer (TGTGCTAAG) and promoter ( TATA box )
- Section R ( redundant ) with a polyadenylation signal (AATAAA) for the formation of a poly (A) tail to stabilize the mRNA (see transcription and gene )
- Section U5 ( unique 5 ')
Functions
LTRs can initiate, amplify, and control transcription. They provide binding sites for transcription factors that are responsible for tissue specificity. But you can also terminate the transcription .
literature
- Susanne Modrow, Dietrich Falke , Uwe Truyen: Molecular Virology. An introduction for biologists and medical professionals. 2nd Edition. Spectrum textbook, Heidelberg 2002, ISBN 3-8274-1086-X . (with references, English translation 2006) .
- David M. Knipe, Peter M. Howley, et al. (Ed.): Fields' Virology . (2 volumes; standard work on virology) 5th edition, Lippincott Williams & Wilkins, Philadelphia 2007, ISBN 978-0-7817-6060-7 .
Individual evidence
- ↑ Beatrice Weber, Tony Heitkam, Daniela Holtgräwe, Bernd Weisshaar, André E. Minoche: Highly diverse chromoviruses of Beta vulgaris are classified by chromodomains and chromosomal integration . In: Mobile DNA . tape 4 , no. 1 , March 1, 2013, ISSN 1759-8753 , p. 8 , doi : 10.1186 / 1759-8753-4-8 .
- ↑ M. Zaratiegui: Influence of long terminal repeat retrotransposons in the genomes of fission yeasts. In: Biochemical Society transactions. Volume 41, Number 6, December 2013, pp. 1629-1633, ISSN 1470-8752 . doi: 10.1042 / BST20130207 . PMID 24256266 .