Structures of the human L1 element and Zorro3 of C. albicans. Shaded boxes represent ORFs; the approximate positions of conserved protein-coding domains are indicated. The ORFs are flanked by untranslated regions (thick black lines). The border between the 3' UTR of each element and flanking genomic DNA (dashed lines) consists of a poly-A tract (An). Zorro3 also has a poly-A sequence at its 5' end and between its ORFs. The L1 element is flanked by short duplications of the target sequence (black triangles).