Eukaryotic genomes are full of long terminal repeat (LTR) retrotransposons. Although most LTR retrotransposons have common structural features and encode similar genes, there is nonetheless considerable diversity in their genomic organization, reflecting the different strategies they use to proliferate within the genomes of their hosts. reports deposited research Transposons are mobile genetic elements that can multiply in the genome using a variety of mechanisms. Retrotransposons replicate through. | Review The diversity of LTR retrotransposons Ericka R Havecker Xiang Gao and Daniel F Voytas Address Department of Genetics Development and Cell Biology Iowa State University Ames IA 50011 USA. Correspondence Daniel F Voytas. E-mail Voytas@ Published 18 May 2004 Genome Biology 2004 5 225 The electronic version of this article is the complete one and can be found online at http 2004 5 6 225 2004 BioMed Central Ltd Abstract Eukaryotic genomes are full of long terminal repeat LTR retrotransposons. Although most LTR retrotransposons have common structural features and encode similar genes there is nonetheless considerable diversity in their genomic organization reflecting the different strategies they use to proliferate within the genomes of their hosts. Transposons are mobile genetic elements that can multiply in the genome using a variety of mechanisms. Retrotrans-posons replicate through reverse transcription of their RNA and integration of the resulting cDNA into another locus. This mechanism of replication is shared with retroviruses with the difference that retrotransposons do not form infectious particles that leave the cell to infect other cells. The long terminal repeat LTR retrotransposons one of the main groups of retroelements which include both LTR and non-LTR retrotransposons as well as retroviruses are among the most abundant constituents of eukaryotic genomes. The LTRs are the direct sequence repeats that flank the internal coding region which - in all autonomous functional LTR retrotransposons - includes genes encoding both structural and enzymatic proteins. The gag gene encodes structural proteins that form the virus-like particle VLP inside which reverse transcription takes place. The pol gene encodes several enzymatic functions including a protease that cleaves the Pol polyprotein a reverse transcriptase RT that copies the retrotransposon s RNA into cDNA and an integrase that integrates the cDNA into the genome. Much of
