#DOTD: Short Interspersed Nuclear Elements

26 Aug 2017

Long + Short Interspersed Nuclear Elements (LINEs + SINEs) make up approximately 21% + 11% of the human genome, respectively. They are non-long terminal repeat (non-LTR) retrotransposons, which means they are transposons that reintegrate themselves within genomes via RNA intermediates (hence, retro), + they are not flanked by long terminal repeats (hence, non-LTR). Note that, in contrast to DNA transposons, retrotransposons use a copy + paste mechanism, thereby extending the genome + repeating within it. LINE's + SINE's only occur in eukaryotic genomes + are hypothesised to have co-evolved.

 

SINEs

  • Less than 700bp long

  • Are known as non-autonomous transposons

  • They contain RNA polymerase III promoters to facilitate their transcription; for their reverse-transcription, they rely on the reverse transcriptase of a LINE element.

  • The most abundant type is the Alu element

Read about LINEs in my previous blog post here + check out my next blog post about Alu elements.

 

[235]

 

References:

Hancks, D.C. and Kazazian, H.H., 2016. Roles for retrotransposon insertions in human disease. Mobile DNA, 7(1), p.9. [Highly recommended.]

https://en.wikipedia.org/wiki/Retrotransposon#Non-LTR_retrotransposons

https://en.wikipedia.org/wiki/Long_interspersed_nuclear_element

https://en.wikipedia.org/wiki/Short_interspersed_nuclear_elements_(SINEs)

https://en.wikipedia.org/wiki/Alu_element

Singer, M.F., 1982. SINEs and LINEs: highly repeated short and long interspersed sequences in mammalian genomes. Cell, 28(3), pp.433-434.

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