KCNJs transport K+ from the extracellular region to cytosol

Stable Identifier
R-HSA-1296046
Type
Reaction [transition]
Species
Homo sapiens
Compartment
Synonyms
Activation of classical Kir channels
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Activation of classical Kir (K+ inwardly rectifying) channels (KCNJ2, 4, 12 and 14) results in K+ influx which contributes to the maintenance of the membrane potential (Phase 4 of the action potential). The current created by this flow of K+ is called the inward rectifying current (IK1). A channel that is inwardly-rectifying is one that passes current more easily into the cell than out of the cell. At membrane potentials negative to potassium's reversal potential, KCNJs support the flow of K+ ions into the cell, pushing the membrane potential back to the resting potential. Two factors regulate K+ permeability - cell permeability to K+ is increased at more negative membrane potentials and increasing extracellular K+ concentrations.

When the membrane potential is positive to the channel's resting potential (such as in Phase 3 of the action potential), these channels pass very little charge out of the cell. This may be due to the channel's pores being blocked by internal Mg2+ and endogenous polyamines such as spermine (Shin & Lu 2005).

Inwardly rectifying (Kir) channels contribute to potassium leak, stabilizing cells near the equilibrium reversal potential of potassium (EK). Kir channels pass small outward currents because of pore blockade by internal magnesium and polyamines; at potentials negative to EK, large inward currents are passed upon relief from blockade.

Literature References
PubMed ID Title Journal Year
15795311 Mechanism of the voltage sensitivity of IRK1 inward-rectifier K+ channel block by the polyamine spermine

Shin, HG, Lu, Z

J. Gen. Physiol. 2005
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
inward rectifier potassium channel activity of KCNJ tetramer [plasma membrane]
Physical Entity
Activity
Orthologous Events
Cross References
Rhea
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