Fig. 1

Occurrence of previously and newly found r-leaders in bacteria and archaea. R-leaders predicted or confirmed to bind various r-proteins are shown along with the phyla or classes in which they occur. R-leaders predicted in “this work, not novel” structurally resemble previously predicted r-leaders (Additional file 1: Figure S1). “same in multiple phyla”: some r-leaders occur in more than one phylum. Multiple letters in a grid point imply multiple motifs, usually for different sub-lineages of the given phylum. eL7, eL15: r-proteins specific to eukaryotes and archaea. The ligands of predicted r-leaders have differing degrees of confidence (e.g., see Table 1), and could be incorrect. Phyla whose r-leaders are all present in other already-shown phyla are not listed, except that Crenarchaeota is depicted. The phyla containing previously identified r-leaders are determined based on previous reports (see Additional file 1: Table S1), and not based on homology searches, because established search parameters are lacking in most cases. Some r-leaders are only identified in a single species or a limited taxa; we depicted these r-leaders as present in the phyla. The figure suggests a conspicuous absence of a S6:S18 r-leader in Alphaproteobacteria; we see promising motifs that likely correspond to the missing r-leaders (Weinberg, unpublished data). The data in this figure are derived from Table 1, Additional file 1: Table S1 and the three motifs in Additional file 1: Figure S1