Figure 16.

Evidence that Zn²⁺ binds with high affinity at the interface between the two monomers in the dimeric human proton channel. The Zn²⁺ dependence of the slowing of channel opening (τ_act) by Zn²⁺ is plotted for WT hH_V1 and six related constructs in which one or both of the key His residues, His¹⁴⁰ and His¹⁹³, were replaced with Ala, including three tandem dimers. Inset cartoons show His as solid, Ala as open, with circles for position 140 and squares for position 193. Slowing occurs only when at least one His is present in each monomer. [From Musset et al. (360).]