Fission yeast retrotransposon Tf1 integration is targeted to 5 ' ends of open reading frames

Target site selection of transposable elements is usually not random but in volves some specificity for a DNA sequence or a DNA binding host factor. We have investigated the target site selection of the long terminal repeat-co ntaining retrotransposon Tf1 from the fission yeast Schizosaccharomyces pom be. By monitoring induced transposition events we found that Tf1 integratio n sites were distributed throughout the genome. Mapping these insertions re vealed that Tf1 did not integrate into open reading frames, but occurred pr eferentially in longer intergenic regions with integration biased towards a region 100-420 bp upstream of the translation start site. Northern blot an alysis showed that transcription of genes adjacent to Tf1 insertions was no t significantly changed.