K_V1.5 is a mammalian voltage dependent K⁺ channel, homologous to the Drosophila Shaker K⁺ channel. K_V1.5 was first cloned from the rat brain.¹ Eight Shaker related genes exist in mammals constituting the K_V1 subfamily of the large K_V channel family of genes.²

A functional K_V1 channel is either a membrane spanning homotetramer or heterotetramer, which is composed of members of the same subfamily. In addition several auxiliary subunits and intracellular proteins might interact with the channel and affect its function.

The structure of K_V1.5 channel is similar to all K_V channels and includes six membrane spanning helices creating a voltage sensor domain and a pore domain.²

The channel is expressed in cardiac and smooth muscle tissue (colon, aorta, stomach and pulmonary artery) as well as in neurons and kidney.² A loss-of-function mutation in the gene encoding the channel was found in atrial fibrillation patients, stressing its role as a cardiac action potential regulator.³

The functional channel is considered transient (A-type) channel and shows prominent inactivation. Therefore, this channel activity influences the membrane potential and excitability of neurons and muscle.

K_V1.5 channels are sensitive to high doses of TEA (330 mM) and low doses of 4-AP (0.27 mM), the “classical” non-selective potassium channel blockers.²