Modulation of Kv4.3 current by accessory subunits

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Abstract
Kv4.3 encodes the pore‐forming subunit of the cardiac transient outward potassium current (I to). hKv4.3‐encoded current does not fully replicate cardiac I to, suggesting a functionally significant role for accessory subunits. KChIP2 associates with Kv4.3 and modifies hKv4.3‐encoded currents but does not replicate native I to. We examined the effect of several ancillary subunits expressed in the heart on hKv4.3‐encoded currents. Remarkably, the ancillary subunits Kvβ3, minK, MiRP‐1, the Na channel β1 and KChIP2 increased the density and modified the gating of hKv4.3 current. hKv4.3 promiscuously assembles with ancillary subunits in vitro, functionally modifying the encoded currents; however, the physiological significance is uncertain.