Maximum likelihood phylogenetic trees (a) of archaeal valyl-tRNA synthetases and (b) of leucyl aminopeptidases representing the three domains of life and including all the known archaeal sequences. Numbers indicate bootstrap support based on 100 replicates. Where the value was <50, the branch was collapsed. The scale bar indicates the inferred number of substitutions per site. The sequence alignments used to generate the trees are provided in the Additional data file 4.
Podar et al. Genome Biology 2008 9:R158 doi:10.1186/gb-2008-9-11-r158