K_V12.3 (also known as KCNH4, Elk3) is a voltage-gated K⁺ channel that belongs to the ether-a-go-go (EAG) family. The EAG family of voltage-gated K⁺ channels can be subdivided into three distinct groups based on sequence homology. These are the eag (K_V10) with two members, the eag-related channels (erg or K_V11) and the eag-like K⁺ channels (elk or K_V12) with three members each.

As with all members of the family, K_V12.3 possesses the signature structure of the voltage-dependent K⁺ channels: six membrane-spanning domains with intracellular N- and C- termini. The functional channel is a tetramer composed of four subunits. It has been suggested that the K_V12 subfamily members can form functional heteromultimers within the subfamily.^1,2

K_V12.3 channel distribution appears to be mainly confined to the central nervous system with some expression in peripheral organs such as the testis and lung.³

The physiological function of the K_V12.3 channel is yet to be established, although a role in the modulation of overall excitability of neurons has been suggested.³  

Currently, there isn’t much pharmacological data concerning the modulation of the K_V12.3 channel except for blocking of the channel by Ba²⁺.³