R294H-A351H forms a high affinity Zn binding site that reduces current magnitude

(A) Representative current traces from an oocyte expressing Kv1.2-R294H-A351H channels recorded in the absence (left) and presence (right) of 1 μM Zn, using the protocol outlined in the Materials and methods. Black arrowheads indicate where steady-state current was measured to generate and relationships. (B) Mean current–voltage relationships from oocytes expressing Kv1.2-R294H-A351H channels recorded in the absence (solid squares, 8) and presence (open circles, 8) of 1 μM Zn. (C) Normalized curves for Kv1.2-R294H-A351H obtained in the absence (black squares, = 8) and presence of various concentrations of Zn; 10 nM (gray triangles, = 7), 100 nM (open diamonds, = 7), and 1 μM (open circles, = 8) showing dose-dependent reduction in conductance with increasing concentrations of extracellular Zn. To demonstrate loss of current with Zn application, conductance () values obtained in either the absence or presence of Zn were normalized to the maximal value obtained in the absence of Zn. Data for control (no Zn) and 10 nM Zn were fitted with a single Boltzmann function, shown as solid black and gray curves respectively. (D and E) Normalized curves obtained in the absence (solid squares) and presence (open circles) of 1 μM Zn for (D) Kv1.2-R294H ( = 9) and (E) Kv1.2-A351H ( = 8). Single mutants showed no loss of current magnitude with application of 1 μM Zn; hence values were normalized to the maximal in each experimental condition (absence or presence of Zn).

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Taken from "Atomic Constraints between the Voltage Sensor and the Pore Domain in a Voltage-gated K Channel of Known Structure"

The Journal of General Physiology 2008;131(6):549-561.

Published online Jan 2008

PMCID:PMC2391244.