K_V11.3 (erg3) is a member of the ether-a-go-go (EAG) subfamily of voltage-dependent K⁺ channels. The erg subfamily includes the closely related proteins K_V11.1 (erg1) and K_V11.2 (erg2) that possess the signature structure of the voltage-dependent K⁺ channels: six membrane-spanning domains with intracellular N- and C-termini. As with all voltage-dependent K⁺ channels, the functional channel is a tetramer composed of four subunits. It has been suggested that the K_V11 subfamily members can form functional heteromultimers within the subfamily.

The current of the K_V11.1 and K_V11.2 channels is that of a strong inward rectifier with slow activating kinetics. The K_V11.3 channel has different biophysical properties: it is a weak inward rectifier that is activated at negative potentials and has rapid activating kinetics.

K_V11.3 expression is believed to be concentrated mainly in the brain with the stronger expression detected in the cerebral cortex and hippocampus.

Currently, there is not much pharmacological information concerning K_V11.3 modulation, but the channel has been shown to be inhibited (as are all K_V11 subfamily members) by the anti-arrhythmic E-4031 as well as by the anti-psychotic drugs sertindole and pimozide.