Episodic ataxia type 1 (EA1) is a Shaker-like channelopathy characterized by continuous myokymia and attacks of imbalance with jerking movements of the head, arms, legs. Although altered expression and gating properties of Kv1.1 channels underlie EA1, several disease causing mechanisms remain poorly understood. Kv1.1, Kv1.4 and, Kv1.1 subunits likely form heteromeric channels at hippocampal mossy fiber boutons from which Zn²⁺ ions are released into the synaptic cleft. The sensitivity of this macromolecular channel complex to Zn²⁺ is unknown. Here we show that this heteromeric channel possesses a high affinity (<10 µM) and a low affinity (<0.5 mM) site for Zn²⁺ ions. Furthermore, the EA1 mutation F184C decreased the equilibrium dissociation constants for Zn²⁺ binding to both the high affinity and low affinity sites, markedly. The functional characterization of the Zn²⁺ effects on heteromeric F184C channels also showed that this ion significantly: i) slowed the activation rate of the channel; ii) increased the time to peak current amplitude; iii) decreased the rate and the amount of current undergoing N-type inactivation; iv) slowed the repriming of the channel compared to wild-type. These results demonstrate that the EA1 mutation F184C will not only sensitise homomeric Kv1.1 channel to extracellular Zn²⁺ but will also endow heteromeric channels with a higher sensitivity to this metal ion. During the vescicular release of Zn²⁺ its effects will be additional to the intrinsic gating defects caused by the mutation that likely exacerbates the symptoms by impairing the integration and transmission of signals within specific brain areas.