LRE2, an active human L1 element, has low level transcriptional activity and extremely low reverse transcriptase activity
- Univ. of Pennsylvania School of Medicine, Philadelphia, PA (United States); and others
Previously, we found a 2 kb insertion containing a rearranged L1 element plus a unique sequence component (USC) within exon 48 of the dystrophin gene of a patient with muscular dystrophy. We used the USC to clone the precursor of this insertion, the second known {open_quotes}active{close_quotes} human L1 element. The locus LRE2 (L1 Retrotransposable Element 2) has an allele derived from the patient which matches the insertion sequence exactly. LRE2 has a perfect 13-15 bp target site duplication, 2 open reading frames (ORFs), and an unusual 21 bp truncation of the 5{prime} end in a region known to be important for L1 transcription. The truncated LRE2 promoter has about 20% of the transcriptional activity of a previously studied L1 promoter after transfection into NTera2D1 cells of a construct in which the L1 promoter drives the expression of a lacZ gene. In addition, the reverse transcriptase (RT) encoded by LRE2 is active in an in vivo pseudogene assay in yeast and an in vitro assay. However, in both assays the RT of LRE2 is 1-5% as active as that of LRE1. These data demonstrate that multiple {open_quotes}active{close_quotes} L1 elements exist in the human genome, and that active elements can have highly variable rates of transcription and reverse transcriptase activity. That the RT of LRE2 has extremely low activity suggests the possibility that retrotransposition of an L1 element may in some cases involve an RT encoded by another L1 element.
- OSTI ID:
- 133839
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0572
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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