KCNJ2 — Kir2.1 Inward Rectifier Potassium Channel
Overview
flowchart TD
KCNJ2["KCNJ2"] -->|"expressed in"| endothelial_cell["endothelial cell"]
KCNJ2["KCNJ2"] -->|"regulates"| membrane_potential["membrane potential"]
KCNJ2["KCNJ2"] -->|"expressed in"| Brain_Capillary_Endothelial_Ce["Brain Capillary Endothelial Cells"]
KCNJ2["KCNJ2"] -->|"regulates"| Neurovascular_Coupling["Neurovascular Coupling"]
KCNJ2["KCNJ2"] -->|"inhibits"| Traumatic_Brain_Injury["Traumatic Brain Injury"]
KCNJ2["KCNJ2"] -->|"inhibits"| Als["Als"]
KCNJ2["KCNJ2"] -->|"inhibits"| Dementia["Dementia"]
KCNJ2["KCNJ2"] -->|"inhibits"| Amyotrophic_Lateral_Sclerosis["Amyotrophic Lateral Sclerosis"]
KCNJ2["KCNJ2"] -->|"inhibits"| neurodegeneration["neurodegeneration"]
KCNJ2["KCNJ2"] -->|"inhibits"| frontotemporal_dementia["frontotemporal dementia"]
KCNJ2["KCNJ2"] -->|"participates in"| CRISPR_Cas["CRISPR-Cas"]
KCNJ2["KCNJ2"] -->|"expressed in"| neurons["neurons"]
TAU["TAU"] -->|"inhibits"| KCNJ2["KCNJ2"]
C9ORF72["C9ORF72"] -->|"inhibits"| KCNJ2["KCNJ2"]
style KCNJ2 fill:#4fc3f7,stroke:#333,color:#000
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KCNJ2 — Kir2.1 Inward Rectifier Potassium Channel
Overview
Mermaid diagram (expand to render)
KCNJ2 (Potassium Inwardly Rectifying Channel Subfamily J Member 2) encodes Kir2.1, a member of the inward rectifier potassium channel family. These channels play critical roles in maintaining resting membrane potential and controlling cellular excitability in neurons and cardiac myocytes. The gene is located on chromosome 17q24.3 and encodes a 493-amino acid protein. Kir2.1 channels are essential for normal neuronal function, and dysregulation has been implicated in both Alzheimer's disease and Parkinson's disease.
<div class="infobox infobox-gene">
Protein Structure and Function
Structural Features Kir2.1 is a member of the inward rectifier potassium channel family with distinctive structural features:
Transmembrane domains : Two transmembrane helices (M1 and M2) that form the channel poreP-loop : Pore helix and selectivity filter between M1 and M2 with the highly conserved GYG sequenceCytoplasmic termini : Large N-terminal and C-terminal domains that comprise most of the protein massThe channel assembles as a tetramer, with each subunit contributing to the formation of a central pore.
Inward Rectification Mechanism The defining feature of Kir2.1 is strong inward rectification:
Mg²⁺ block : Intracellular magnesium ions block the channel at positive membrane potentialsPolyamine block : Spermine and spermidine contribute to strong rectificationVoltage-dependent gating : The channel conducts K⁺ more efficiently at negative potentials
Expression Pattern
Brain Expression KCNJ2 shows widespread expression throughout the nervous system:
Cerebral cortex : High expression in pyramidal neuronsHippocampus : Prominent in CA1-CA3 neurons and dentate gyrusBasal ganglia : Moderate expression including striatum and substantia nigraCerebellum : Purkinje cells show significant expressionOther Tissues
Heart : High expression in cardiac ventricles and atriaSkeletal muscle : Very high expressionPancreas : Moderate expressionDisease Associations
Andersen-Tawil Syndrome (ATS) KCNJ2 is the causative gene for Andersen-Tawil syndrome type 1 (ATS1):
Periodic paralysis : Episodic weakness, often triggered by restCardiac arrhythmias : Prolonged QT interval, ventricular ectopyDevelopmental abnormalities : Short stature, skeletal anomaliesAlzheimer's Disease The involvement of KCNJ2 in AD relates to:
Neuronal potassium homeostasis : Kir2.1 dysfunction affects resting membrane potentialNetwork hyperexcitability : Altered Kir2.1 contributes to network dysfunction in early AD
Parkinson's Disease KCNJ2 involvement in PD includes:
Dopaminergic neuron function : Kir2.1 regulates resting membrane potential of substantia nigra neuronsExpression changes : Altered KCNJ2 expression observed in PD models
Therapeutic Implications | Approach | Description | Status |
Research Directions
Developing selective pharmacological modulators
Gene therapy approaches for channelopathies
Linking Kir2.1 dysfunction to specific neurodegenerative mechanisms
References
[Plaster NM, et al., Mutations in KCNJ2 cause Andersen-Tawil syndrome (2001)](https://pubmed.ncbi.nlm.nih.gov/11418765/)
[Lopatin AN, et al., Molecular basis of inward rectification in Kir channels (2001)](https://pubmed.ncbi.nlm.nih.gov/11299044/)
[Niehusmann P, et al., Kir2.1 dysfunction in Alzheimer's disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30959507/)
See Also
[KCNJ12 Gene](/genes/kcnj12) — Related inward rectifier channel
[Potassium Channel Genes](/genes) — Gene family overview
[Ion Channelopathies](/diseases/ion-channelopathies)
Pathway Diagram The following diagram shows the key molecular relationships involving KCNJ2 — Kir2.1 Inward Rectifier Potassium Channel discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
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