Fig. 2
Tj1 is an active LTR-retrotransposon and likely relies of self-priming to initiate reverse transcription. a The structure of Tj1 is shown. Indicated are the positions of LTRs, and the coding sequences for Gag, PR, RT, and IN. The primer binding site (PBS) and the polypurine tract (PPT) are shown. b Sequence from the 5' LTR is shown indicating the upstream region that has complementarity to the PBS. We propose this serves as a self-primer of reverse transcription. Also shown is the potential cleavage site that is necessary to initiate priming of reverse transcription. c The FOA/G418 plates from the transposition assay. Left Panel: the top row shows transposition activity of Nmt1-Tf1-neo controls expressing wild type Tf1-neo, Tf1-neo with the protease frameshift (PRfs), and Tf1-neo with the integrase frameshift (INfs). Rows 2 and 3 each contain 4 independent transformants of Nmt1-Tj1-neo. Rows 4 and 5 each contain 4 transformants of Tj1-neo expressed from the Tj1 promoter. Growth of the patches is a measure of transposition frequency. Right Panel: The top row contains the Nmt1-Tf1-neo controls. In the second row the patch on the left contains Tj1-neo. The patch on the right side of the second row and the two patches on the 3rd row are three independent transformants of Tj1-neo with a mutation that removes the stop codon at the end of Gag and as a result fuses all coding sequence into one ORF (Tf1-neo TGAx)