Fig. 2.

Conservation of the protein structure is reflected in the conservation of codon usage profile. Backbone/cartoon structures of the phosphoglycerate kinases (PGK) from Escherichia coli (PDB ID 1ZMR) (top), from Saccharomyces cerevisiae yeast (PDB ID 3PGK) (center), and from mouse, Mus musculus (PDB ID 2P9T) (bottom). The respective codon usage profiles are on the right (N- and C-terminal domain boundaries are indicated). Red arrows indicate the conserved cluster of rare codons at the domain boundaries region.