Fig. 3. Comparison of the active sites of trout cytoplasmic catalytic anhydrase (CA) with those of trout red blood cell CA (TCAb), dace CA, gar CA, concensus trout CA I, CA II and human CA VII. Identical amino acids are indicated by a dot. aa diff, number of amino acid differences. ^*, putative active site; z, zinc binding ligand; +, proton shuttling associated ligand; , substrate associated pocket.