Examination of engineered LINE-1 integration events in HeLa cells

Long Interspsesed Element-1 (LINE1 or L1) encodes two proteins (ORF1p and ORF2p) required for its mobilization (i.e. retrotransposition) in the human genome. Human ORF2p, a 150kDa protein, has endonuclease (EN) and reverse transcriptase (RT) activities. L1 EN is classified as apurinic/apyrimidin-like endonuclease (APE) and is responsible for initiating target-site primer reverse transcription (TPRT) during the L1 retrotransposition cycle. During canonical TPRT, the L1 EN activity makes a single-strand endonucleolytic nick at a double-strand DNA target sequence in genomic DNA. The endonucleolytic nick is typically made at an L1 EN degnerate consensus cleavage sequence (5'-TTTT/A-3') exposing a free 3' hydroxy group that can be used as a primer by the ORF2p L1 RT activity to reverse... (for more see dbGaP study page.)