Kir2.3 is a member of the family of inward rectifying K+ channels. The family includes 15 members that are structurally and functionally different from the voltage-dependent K+ channels.
The family’s topology consists of two transmembrane domains that flank a single and highly conserved pore region with intracellular N- and C-termini. As is the case for the voltage-dependent K+ channels the functional unit for the Kir channels is composed of four subunit that can assembly as either homo or heterotetramers.
Kir channels are characterized by a K+ efflux that is limited by depolarizing membrane potentials thus making them essential for controlling resting membrane potential and K+ homeostasis.
Kir2.3 is a member of the Kir2.x subfamily that includes four members (Kir2.1- Kir2.4) that are characterized by strong inward rectification and high constitutive activity.
Kir2.3 is expressed in a variety of tissues including heart and brain. 2
In the heart, Kir2.3 forms heteromers with Kir2.1 and underlay the IK1 current (at least in some species) that is responsible for setting the resting membrane potential, preventing membrane hyperpolarization due to Na+ pump activity, influencing propagation velocity, altering the electrical space constant, and promoting late phase repolarization.1,2
