Current states and inferred evolutionary process of electric charge change in PGI isoforms. (A) Maximum likelihood tree of Pgi genes in ray-finned fishes inferred by BASEML  with a known phylogeny . Numbers indicate estimated pI. Arrow denotes a gene duplication event. (B) Amino acid sites that differ by the presence or absence of hydrophilic charged residues between current PGI-1 and PGI-2. Positively charged residues are blue; negatively charged residues, red; other residues, light gray. The numbers above refer to the amino acid positions of PGI . The stars below indicate sites located on the molecular surface. (C) Inferred charge-changing substitution events mapped over the PGI phylogeny. Orange and brown bars denote upward and downward charge changes, respectively.