Short interspersed nuclear element

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Under short interspersed nuclear elements ( SINE , Eng. For short, interspersed core sequence elements') is understood to typically 100 to 400 base pairs long, often repeated and relatively freely distributed DNA sequences in the genome . SINEs are often counted among the transposable elements that use an RNA as an intermediate stage ( retro element ) and have no long terminal repeats (non-LTR retrotransposons ). However, transposable elements in the narrower sense are defined as DNA sequences which themselves encode a transposase and thus have an intrinsic ability to change their genomic position. In contrast to the longer LINEs , SINEs are not autonomous, but require an external reverse transcriptase (often encoded by LINEs), as they do not (or no longer) have their own.

SINEs often match LINE sequences in the 3 'sequence and are often degenerate genes for small RNAs , such as 7SL-RNA , or tRNAs . tRNA-related SINEs have a composite structure with a region that is homologous to a tRNA, a non-tRNA-like region, and a variable (8-50 bp ) AT-rich 3 'end. The tRNA-homologous sequence includes a RNA polymerase III - promoter . They are accordingly transcribed by RNA polymerase III .

An important SINE family is the so-called Alu family , which only occurs in primates . Other families occur in all mammals (including monotons and marsupials ) and are therefore also referred to as mammalian-wide interspersed repeats (MIR). In some organisms, such as For example, the fruit fly Drosophila melanogaster or the nematode Caenorhabditis elegans lack SINEs.

SINEs make up about 14% in the human genome.

SINEs are also found in many plant genomes. For example, SINEs are widespread in various types of grain in high diversity and with varying numbers of copies.

literature

  • P. Capy, C. Bazin, inter alia: Dynamics and Evolution of Transposable Elements. Landes Bioscience and Chapman & Hall, 1998.

Individual evidence

  1. ↑ TH Eick Bush, AV Furano: Fruit flies and humans respond differently to retrotransposons. In: Current opinion in genetics & development. Volume 12, Number 6, December 2002, pp. 669-674, ISSN  0959-437X . PMID 12433580 . (Review).
  2. ↑ Torsten Wenke, Thomas Döbel, Thomas Rosleff Sörensen, Holger Junghans, Bernd Weisshaar: Targeted Identification of Short Interspersed Nuclear Element Families Shows Their Widespread Existence and Extreme Heterogeneity in Plant Genomes [W] . In: The Plant Cell . tape 23 , no. 9 , September 2011, ISSN  1040-4651 , p. 3117-3128 , doi : 10.1105 / tpc.111.088682 , PMID 21908723 , PMC 3203444 (free full text).
  3. ↑ Anja Kögler, Thomas Schmidt, Torsten Wenke: Evolutionary modes of emergence of short interspersed nuclear element (SINE) families in grasses . In: The Plant Journal . tape 92 , no. 4 , November 1, 2017, ISSN  1365-313X , p. 676-695 , doi : 10.1111 / tpj.13676 .