title: A novel active L1 retrotransposon subfamily in the mouse.
abstract: Unlike human L1 retrotransposons, the 5' UTR of mouse L1 elements contains tandem repeats of approximately 200 bp in length called monomers. Multiple L1 subfamilies exist in the mouse which are distinguished by their monomer sequences. We previously described a young subfamily, called the T(F) subfamily, which contains approximately 1800 active elements among its 3000 full-length members. Here we characterize a novel subfamily of mouse L1 elements, G(F), which has unique monomer sequence and unusual patterns of monomer organization. A majority of these G(F) elements also have a unique length polymorphism in ORF1. Polymorphism analysis of G(F) elements in various mouse subspecies and laboratory strains revealed that, like T(F), the G(F) subfamily is young and expanding. About 1500 full-length G(F) elements exist in the diploid mouse genome and, based on the results of a cell culture assay, approximately 400 G(F) elements are potentially capable of retrotransposition. We also tested 14 A-type subfamily elements in the assay and estimate that about 900 active A elements may be present in the mouse genome. Thus, it is now known that there are three large active subfamilies of mouse L1s; T(F), A, and G(F), and that in total approximately 3000 full-length elements are potentially capable of active retrotransposition. This number is in great excess to the number of L1 elements thought to be active in the human genome.
authors.affiliation: Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA. jgoodier@mail.med.upenn.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Goodier
authors.forename: E M
authors.initials: EM
authors.lastname: Ostertag
authors.forename: K
authors.initials: K
authors.lastname: Du
authors.forename: H H
authors.initials: HH
authors.lastname: Kazazian
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D006367:HeLa Cells; D006801:Humans; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions