| Transposition begins with the transcription of the LINE element (red) into RNA (blue) which encodes an RNA binding protein and a multifunctional protein with endonuclease and reverse transcriptase activity. These proteins (not shown) associate with the LINE RNA, and the endonuclease nicks the DNA at the target site, which contains a polyT tract which base-pairs with the polyA sequence in the LINE RNA. The LINE RNA is then copied by the reverse transcriptase into a DNA copy (green) which is covalently attached to the target DNA. A second DNA strand is then synthesized on the template of the DNA copy, and the target DNA at each end is filled in to generate the target-site duplications (TSDs) that flank these elements. |
