Figure 7. Mutagenesis studies searching for potential zinc-binding sites in the membrane portion of Kv3.1b.

A, diagram of the membrane portion Kv3.1. All six cysteine (C) and histidine (H) residues in the transmembrane segments and extracellular loops are indicated with asterisks with residue numbers labelled. B, zinc's effects on current amplitudes of different channel mutants. The numbers of HEK293 cells are indicated in parentheses for B–E. C and D, effect of Zn²⁺ on the G–V relationship of the channel mutants. E, zinc's effects on activation time constant (τ_on). Paired t test: **P < 0.01; *P < 0.05.