1731 is a Ty1/Copia LTR retrotransposon characterized in Drosophila melanogaster (Fourcade-Peronnet et al. 1988). It belongs and gives the name to 1731 clade within Branch 2 of the Ty1/Copia family (Llorens et al. 2009). 1731 is 4648 bp in size, including two 336-bp LTRs. This element contains a Primer Binding Site (PBS) for a tRNAiMet, two overlapping Open Reading Frames (ORFs) showing the typical gag and pol domains of Ty1/Copia LTR retrotransposons and a final Polypurine Tract (PPT). The first ORF corresponds to the gag gene, while the second displays the characteristic pol gene structure (protease, integrase, reverse transcriptase and ribonuclease H) (Fourcade-Peronnet et al. 1988; Ziarczyk and Best-Belpomme 1991).
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