Ty3, a Position-specific Retrotransposon in Budding Yeast

Long terminal repeat (LTR) retrotransposons occur throughout eukaryotic phyla, but vary greatly in both the types of elements and the representation among species. The majority of some genomes are composed of these elements. The LTR retrotransposons are taxonomically divided into Pseudoviridae (or Ty1/Copia) and Metaviridae (or Ty3/Gypsy) elements based on genome organization and relatedness of proteins encoded (reviewed in references1–3) (Gypsy Database 2.0, gydb.org). The Ty3/Gypsy family has shared ancestry with retroviruses and some members encode envelope enabling intercellular transmission. The eponymous founding elements of these LTR retrotransposon families, Ty1/Copia and Ty3/Gypsy, exist in Saccharomyces cerevisiae (Ty1 and Ty3) and in Drosophila (Copia and Gypsy).