Fig. 3.

Residues anchoring the RNA 5′ phosphate in human Dicer1 originated in the ancestral animal Dicer. We show sections of aligned ancestral-reconstructed Dicer Platform + PAZ + Connector (PPC) domains from key nodes on the Dicer/DCL protein family phylogeny. Letters in parentheses correspond to node identifiers in figure 1. Residues thought to anchor the RNA’s 3′UU overhang and 5′phosphate in human Dicer1 are indicated by blue and red arrows, respectively (Tian et al. 2014). Identified animal- and plant-specific insertions are also indicated. Complete alignment is shown in supplementary fig. S7, Supplementary Material online. Alternative alignments are shown in supplementary figs. S8 and S9, Supplementary Material online.