Genetic structure of murine LINE1 and SINEs. Bottom: proposed structure of L1 RNA-protein (RNP) complexes. ORF1 proteins form trimers, exhibiting RNA binding and nucleic acid chaperone activity.
LINE1 (also L1 and LINE-1) is a family of related class I transposable elements in the DNA of some organisms, classified with the long interspersed elements (LINEs). L1 transposons comprise approximately 17% of the human genome.[1] These active L1s can interrupt the genome through insertions, deletions, rearrangements, and copy number variations.[2] L1 activity has contributed to the instability and evolution of genomes and is tightly regulated in the germline by DNA methylation, histone modifications, and piRNA.[3] L1s can further impact genome variation through mispairing and unequal crossing over during meiosis due to its repetitive DNA sequences.[2]
L1 gene products are also required by many non-autonomous Alu and SVA SINE retrotransposons. Mutations induced by L1 and its non-autonomous counterparts have been found to cause a variety of heritable and somatic diseases.[4][5]