Identifying related L1 retrotransposons by analyzing 3' transduced sequences

Suzanne T. Szak, Oxana K. Pickeral, David Landsman, Jef D. Boeke

Research output: Contribution to journalArticlepeer-review


Background: A large fraction of the human genome is attributable to L1 retrotransposon sequences. Not only do L1s themselves make up a significant portion of the genome, but L1-encoded proteins are thought to be responsible for the transposition of other repetitive elements and processed pseudogenes. In addition, L1s can mobilize non-L1, 3'-flanking DNA in a process called 3' transduction. Using computational methods, we collected DNA sequences from the human genome for which we have high confidence of their mobilization through L1-mediated 3' transduction. Results: The precursors of L1s with transduced sequence can often be identified, allowing us to reconstruct L1 element families in which a single parent L1 element begot many progeny L1s. Of the L1s exhibiting a sequence structure consistent with 3' transduction (L1 with transduction-derived sequence, L1-TD), the vast majority were located in duplicated regions of the genome and thus did not necessarily represent unique insertion events. Of the remaining L1-TDs, some lack a clear polyadenylation signal, but the alignment between the parent-progeny sequences nevertheless ends in an A-rich tract of DNA. Conclusions: Sequence data suggest that during the integration into the genome of RNA representing an L1-TD, reverse transcription may be primed internally at A-rich sequences that lie downstream of the L1 3' untranslated region. The occurrence of L1-mediated transduction in the human genome may be less frequent than previously thought, and an accurate estimate is confounded by the frequent occurrence of segmental genomic duplications.

Original languageEnglish (US)
JournalGenome biology
Issue number5
StatePublished - May 2003


  • Additional Data File
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Polyadenylation Signal
  • Segmental Duplication
  • Transposable Element

ASJC Scopus subject areas

  • Genetics
  • Ecology, Evolution, Behavior and Systematics
  • Cell Biology


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