Circe is a LTR retrotransposon originally described in the heterochromatic regions of chromosomes III and Y of D. melanogaster, as a tandem organization of defective copies without LTRs (Losada, Abad and Villasante 1997). A later study revealed a sequence accession (AC005427) containing a clone flanked by LTRs, which was used along with two additional accessions (AJ132547 and X98424) to establish a full-length consensus for Circe, which belongs to Osvaldo clade (Malik and Eickbush 1999). The full-length consensus for Circe is 7.4 Kb in size including LTRs of 240 nt. The internal region of this element displays a Primer Binding Site (PBS) for a tRNALys3, three Open Reading Frames (ORFs) for gag, pol, and int genes, and a Polypurine Tract (PPT) adjacent to the 3´LTR (Losada, et al. 1999).
Figure not to scale. If present, long terminal repeats (LTRs) have been highlighted in blue. Amino acid motifs noted with lines indicate the conserved residues in each protein domain, abbreviations below mean:
|DU or DUT=dUTPase
|TAV or IBMP=transactivator/viroplasmin or inclusion body matrix protein
|PBS=primer binding site
|ATF=aphid transmission factor
|VAP=virion associated protein