Probably participates in establishing action potential waveform and excitability of neuronal and muscle tissues. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. Can be blocked by extracellular barium or cesium.
CuratedUniProtKB
According to TCDB this is a transporter from family:
inward rectifier K+ channel (IRK-C) family 1.A.2.1.2
Catalysis of the transmembrane transfer of a potassium ion by an inwardly-rectifying voltage-gated channel. An inwardly rectifying current-voltage relation is one where at any given driving force the inward flow of K+ ions exceeds the outward flow for the opposite driving force. The inward-rectification is due to a voltage-dependent block of the channel pore by a specific ligand or ligands, and as a result the macroscopic conductance depends on the difference between membrane voltage and the K+ equilibrium potential rather than on membrane voltage itself.
We have isolated a cDNA encoding an inwardly rectifying K+ channel (HH-IRK1) from human heart. The cDNA codes for a 427-amino acid protein, with two putative transmembrane domains and an H5 region. The primary structure of HH-IRK1 is homologous to that of the IRK1 channel cloned from a mouse macrophage-like cell line. Functional expression in Xenopus oocytes showed that HH-IRK1 is a K+ channel with strong inward rectification, blocked by extracellular Ba2+ and Cs+, and with a single-channel conductance of 30 pS. Northern analysis showed HH-IRK1 transcripts in human heart, brain, skeletal muscle, placenta, lung and kidney. HH-IRK1 was mapped to human chromosome 17.
Any process that modulates the frequency, rate or extent of action potential creation, propagation or termination in a cardiac muscle cell. An action potential is a spike of membrane depolarization and repolarization that travels along the membrane of a cell.
IEAOrtholog Compara
Pathways
According to KEGG, this protein belongs to the following pathways:
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
Protein which is part of a transmembrane protein complex that forms a hydrophilic channel across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradients. The channels are usually gated and only open in response to a specific stimulus, such as a change in membrane potential (voltage-gated) or the binding of a ligand (ligand-gated channel).
Protein which is a component of a voltage-gated channel. Voltage-gated ion channels are responsible for the electrical activity in a variety of cell types. They probably exist in all life forms.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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