Table 2.

Number of Known or Predicted Domains of Different Structural Classes in Translation Factors in the Tree Primary Divisions of Life

Phyletic distribution[i] Protein structural class
all α-helix all β-sheet[ii] α + β
Eukarya + Archaea + Bacteria—21
Eukarya + Archaea12/2 ancient folds3/1 ancient fold
Eukarya92/2 ancient folds9/8 ancient folds

[i] Instances of likely horizontal transfer (Table 1) were not considered.

[ii] The cases where a lineage-specific initiation factor contains a domain belonging to an ancient fold are shown by “/”.