Fig 1. Evolutionary relationships of taxa for all 172 MIPS sequences.

Prokaryotes and Eukaryotes have a well-defined boundary. Eukaryotic sequences have been denoted by shaded zone. The evolutionary history was inferred using the Neighbor-Joining method [32]. The optimal tree with the sum of branch length = 18.55289526 is shown. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Poisson correction method [33] and are in the units of the number of amino acid substitutions per site. The analysis involved 172 amino acid sequences. All positions containing gaps and missing data were eliminated. There were a total of 222 positions in the final dataset. Evolutionary analyses were conducted in MEGA5 [18].