Biology of mammalian L1 retrotransposons

E. M. Ostertag, Jr Kazazian

Research output: Contribution to journalReview articlepeer-review

577 Scopus citations


L1 retrotransposons comprise 17% of the human genome. Although most L1s are inactive, some elements remain capable of retrotransposition. L1 elements have a long evolutionary history dating to the beginnings of eukaryotic existence. Although many aspects of their retrotransposition mechanism remain poorly understood, they likely integrate into genomic DNA by a process called target primed reverse transcription. L1s have shaped mammalian genomes through a number of mechanisms. First, they have greatly expanded the genome both by their own retrotransposition and by providing the machinery necessary for the retrotransposition of other mobile elements, such as Alus. Second, they have shuffled non-L1 sequence throughout the genome by a process termed transduction. Third, they have affected gene expression by a number of mechanisms. For instance, they occasionally insert into genes and cause disease both in humans and in mice. L1 elements have proven useful as phylogenetic markers and may find other practical applications in gene discovery following insertional mutagenesis in mice and in the delivery of therapeutic genes.

Original languageEnglish (US)
Pages (from-to)501-538
Number of pages38
JournalAnnual review of genetics
StatePublished - Dec 1 2001
Externally publishedYes


  • Genome structure
  • Human mutation
  • Mouse mutation
  • Reverse transcription
  • Transposable elements

ASJC Scopus subject areas

  • Genetics


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