Fig. 2.

Structural organization and phylogenetic relationships of Penelope-like elements (PLE). Shown is the maximum likelihood phylogram based on amino acid sequences of catalytically intact RTs, with TERTs as an outgroup. Structural diagrams are centered on the core RT domain framed by thin dotted lines. Major clades (W, NT, and ILOM) are marked with a bracket; clades with the programmed −1 frameshift are marked by #. PLE clades are as in (Arkhipova 2006; Arkhipova et al. 2013; Lin et al. 2016). Scale bar, amino acid substitutions per site. Detailed ORF composition for each family is shown in supplementary figure S6, Supplementary Material online.