Retrotransposon#LINEs

Under LINEs ( Abbreviation for. Long interspersed nuclear elements ) are understood to typically 6 to 8 kbp long, often repeated and relatively freely distributed DNA sequences in the genome. LINEs belong to the transposable elements that a ribonucleic acid (RNA) as an intermediate use ( retroelement ) and have no long terminal repeat, but multiply by retroposition (these do not count as non- LTR retrotransposons see Retroposon, ). They have the genes for the two proteins: one for binding and transport of the RNA and one with reverse transcriptase activity and one for endonuclease.

LINEs are found on treated by Giemsa staining chromosomes especially in AT- rich regions in the heterochromatin, or in the G bands, see also lifecycle. In humans, LINEs account for about 20 % of the total genome, common elements are LINE-1, LINE -2 and LINE - third

Life cycle of the LINE-1

L1 has the genes for the two proteins: one, which binds RNA ( p40 ) and one which has both a reverse transcriptase activity and an endonuclease ( p150 ). The special feature is that the promoter for transcription in the 5'- UTR of LINEs, ie " inside " is.

The internal promoter initiates the transcription by RNA polymerase II of himself and the two proteins. After translation, the proteins encoded by the mRNA to mRNA store. Said endonuclease cuts in a target sequence in the DNA (often a oligo (dT) ), thus generating a free 3' -OH, which in turn serves as a primer for transcription of the reverse. At this oligo ( T), the oligo ( A) tail superimposed on ( a function of the poly ( A) tail ), so that the LINE mRNA can serve as a template. Often, the reverse transcriptase will not migrate to the 5 'end of the LINE die but before breaks down, therefore, only a small part L1 of the genome is not capable of jumping.

As the integration and synthesis of the second strand takes place is still unknown.