Tit for tat type 2 (Tft2) is a retrotransposon described along with Tft1 in the genome of Arabidopsis thaliana (Marín and Lloréns 2000). This element belongs to a lineage of plant LTR retrotransposons (Tat), sibling of other lineage of putative plant endogenous retroviruses (Athila), providing evidence of a shared ancestral lineage originally described as class A by Wright and Voytas (1998). Tft2 has several subtypes, the Tft2 sequence available in the genbank accession AC018928 is taken as a representative. This clone is 13.2 Kb in size including LTRs of 0.5Kb. The internal region of this element displays a Primer Binding Site (PBS) complementary to a tRNA Arg, four Open Reading Frames (ORFs) for gag, pro, and pol genes, and a Polypurine Tract (PPT) adjacent to the 3´LTR (Marín and Lloréns 2000). As other Tat-like elements, Tft2 displays downstream to the integrase domain an untranslated region of 8 Kb from which little is known.
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