Figure 1.

Ctr2 appearance through evolution as a uniquely metazoan gene. A, Ctr protein sequences from the indicated species were identified and retrieved from the NCBI Protein database by iterative BLAST searches. Sequences were aligned with MUSCLE and subjected to TreeBeST analysis to reveal which species possesses predicted Ctr1 and/or Ctr2. The species tree was created from the NCBI Taxonomy database. A blue dot represents the predicted appearance of Ctr2, whereas the red dot represents the predicted loss of Ctr2. Species classification is shown on the right. B, S. cerevisiae ctr1Δctr3Δ cells were transformed with the indicated plasmids and plated on the indicated medium. Sp, Strongylocentrotus purpuratus. C, the same yeast strains as in B were inspected by fluorescence microscopy and photographed. DIC, differential interference contrast.