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Journal of Biomedicine and Biotechnology
Volume 2006, Article ID 13569, 3 pages
Mini-Review Article

Links Between Repeated Sequences

Division of Microbiology, National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan

Received 23 May 2005; Revised 28 September 2005; Accepted 2 October 2005

Copyright © 2006 Sachiko Matsutani. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


L1 and Alu elements are long and short interspersed retrotransposable elements (LINEs and SINEs) in humans, respectively. Proteins encoded in the autonomous L1 mediate retrotransposition of the nonautonomous Alu and cellular mRNAs. Alu is the only active SINE in the human genome and is derived from 7SL RNA of signal recognition particle. In the other eukaryotic genomes, various tRNA- and 5S rRNA-derived SINEs are found. Some of the tRNA- and 5S rRNA-derived SINEs have partner LINEs of which 3' sequences are similar to those of the SINEs. One of the tRNA-derived SINEs is shown to be mobilized by its partner LINE. Many copies of tRNA and 5S rRNA pseudogenes are present in the human genome. These pseudogenes may have been generated via the retrotransposition process using L1 proteins. Although there are no sequence similarities between L1 and Alu, L1 functionally links with Alu and even cellular genes, impacting on our genome shaping.