MinK channels: A minimal channel protein with a maximal impact

MinK channels represent a family of voltage-gated potassium channels with a very distinct molecular structure and unique kinetic properties. The minK channel subunit contains only one transmembrane-spanning region, but the mechanism of channel formation remains unclear. There is some indication that assembly of the subunits plays a role in channel activation which may also explain the very slow activation kinetics of minK channels. MinK channels are regulated by a number of second messengers such as [Ca²⁺]_i, cyclic-AMP and diacylglycerol also known to modulate cell excitability. This regulation indicates the putative role of minK channels in the modulation of cell excitability in the tissues where they are expressed. In cardiac myocytes, the potassium conductance I_Ks displays similar properties to minK channels expressed in Xenopus oocytes. As this conductance plays a crucial role for the induction of action potential repolarization, it could be a very important target for agents meant to suppress heart rhythm disturbances. Clarification of the minK channel structure and the physiological significance of this channel remains a very important goal.