Figure 3.

The genomic organization of different types of LTR retrotransposon. Abbreviations: IN, integrase; LARDs, large retrotransposon derivatives; ORF, open reading frame; PBS, primer-binding site; PPT, polypurine tract; PR, protease; RT, reverse transcriptase; TRIMs, terminal-repeat retrotransposons in miniature. The upside-down text indicates that the ORF is transcribed in the antisense direction. See text for descriptions of each type of element.