(A) Bayesian phylogenetic tree of SPCs. Numbers represent posterior probability. The stramenopile Aureococcus anophagefferens, denoted by the blue star, has EEVS and MT-Ox proteins strikingly similar (over 50% identical) to those in vertebrates. The micro algae Coccomyxa subellipsoidea, denoted by the red star, also has EEVS and MT-Ox. (B) Genetic organizations of EEVS and MT-Ox genes in fish, amphibians, birds, and reptiles. Humans and other mammals lack these genes (indicated in dashed red box). For a complete list of vertebrates whose genomes are known to contain EEVS and MT-Ox genes, see Table 1. FRMD4B, FERM domain-containing protein 4B; MitF, microphtalmia-associated transcription factor; MDFIC, MyoD-family inhibitor domain-containing protein-like; and FoxP1, Forkhead-related transcription factor 1. (C) Biochemical characterization of recombinant LOC100003999 and zgc:113054 proteins. (D) WebLogo (Crooks et al., 2004) images of residue conservation patterns at the three metal ligand positions and two active site fingerprint sites known (Kean et al., 2014) to distinguish bacterial EEVSs from DDGSs. The residue numbers given correspond to the reference proteins D. rerio EEVS, ValA, and A. variabilis DDGS, respectively. WebLogos were based on 126 vertebrate, 63 bacterial EEVS, and 160 bacterial DDGS sequences, respectively, that had BLASTP E-values <10−120 in searches using the reference proteins noted above as queries. Each group was aligned using ProMals (Pei and Grishin, 2007).