FIGURE 3.

Location of the mutations on Phormidium PC. Only those mutants having the greatest effects are shown. In the absence of the Zn²⁺ ion (Table 2), results are shown for class I (greatest stimulation) and class V (greatest inhibition; in the absence of Zn²⁺ (Table 3), results are shown for class II (greatest stimulation) and classes IV and V (greatest inhibition). (Black) Y88, H92, and the Zn²⁺ (when present); (red) anionic residues; and (blue) cationic residues. (Left) −Zn²⁺ and (right) +Zn²⁺. (Top) Front and (bottom) back of the PC molecules.