I(KACh) inward rectifier potassium channel complex

Definition

Target type: cellularcomponent

An inward rectifier potassium channel complex expressed in cardiac muscle, specifically the sinoatrial node and atria, where it controls the heart rate, via regulation by G protein-coupled receptor signaling. In mammals it is composed of GIRK1 (or Kir3.1) and GIRK4 (or Kir3.4) subunits. [GOC:ame, PMID:9765280]

The I(KACh) inward rectifier potassium channel complex is a multi-protein assembly that plays a crucial role in regulating potassium ion permeability across the cell membrane. The complex is typically found in the plasma membrane of excitable cells, particularly neurons and cardiac myocytes, where it contributes to the resting membrane potential and the repolarization phase of action potentials. The core of the complex is formed by four subunits of the Kir3.x family (also known as GIRK channels), which assemble as a tetramer to create a central pore that allows potassium ions to pass through. Each Kir3.x subunit comprises two transmembrane domains, a pore loop that lines the ion conduction pathway, and intracellular N- and C-terminal domains that interact with other proteins. In addition to the Kir3.x subunits, the I(KACh) complex often includes accessory proteins, such as the G protein-coupled receptor kinase 2 (GRK2), which phosphorylates the channel and regulates its activity. Furthermore, the complex can associate with scaffolding proteins, like AKAPs, which tether the channel to specific subcellular compartments and facilitate its interaction with other signaling molecules. The I(KACh) complex is regulated by a variety of mechanisms, including changes in membrane potential, phosphorylation state, and interaction with intracellular signaling molecules. This intricate regulation allows the channel to fine-tune potassium permeability and contribute to a wide range of physiological processes, including neuronal excitability, cardiac rhythm, and hormone secretion.'
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Proteins (2)

Compounds (6)