RT Journal
A1 Schmitz, Jürgen
A1 Churakov, Gennady
A1 Zischler, Hans
A1 Brosius, Jürgen
T1 A Novel Class of Mammalian-Specific Tailless Retropseudogenes
JF Genome Research 
JO Genome Research 
YR 2004 
FD October 01 
VO 14 
IS 10a 
SP 1911 
OP 1915 
DO 10.1101/gr.2720104 
UL http://genome.cshlp.org/content/14/10a/1911.abstract 
AB In addition to their central function in protein biosynthesis, tRNAs also play a pervasive role in genome evolution and architecture because of their extensive ability to serve as templates for retroposition. Close to half of the human genome consists of discernible transposable elements, a vast majority of which are derived from RNA via reverse transcription and genomic integration. Apart from the presence of direct repeats (DRs) that flank the integrated sequence of retroposons, genomic integrations are usually marked by an oligo(A) tail. Here, we describe a novel class of retroposons that lack A-tails and are therefore termed tailless retropseudogenes. Analysis of ∼2500 tRNA-related young tailless retropseudogene sequences revealed that they comprise processed and unprocessed (pre-)tRNAs, 3′-truncated in their loop regions, or truncated tRNA-derived SINE RNAs. Surprisingly, their mostly nonrandom integration is dependent on the priming of reverse transcription at sites determined by their 3′-terminal 2-18 nucleotides and completely independent from oligoadenylation of the template RNA. Thus, tailless retropseudogenes point to a novel, variant mechanism for the biogenesis of retrosequences.