Potassium Voltage-Gated Channel Subfamily Q Member 3
| KCNQ3 (Kv7.3) | |
|---|---|
| Gene | [KCNQ3](/genes/kcnq3) |
| UniProt ID | [O43525](https://www.uniprot.org/uniprot/O43525) |
| PDB Structures | 5CMS, 6CSX |
| Molecular Weight | 95.5 kDa |
| Subcellular Localization | Neuronal plasma membrane, axon initial segment, synapses |
| Protein Family | Voltage-gated potassium channel (Kv7/KCNQ) |
| Function | Voltage-gated potassium channel, M-current regulation |
KCNQ3 Protein is a protein. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
The KCNQ3 protein is a voltage-gated potassium channel subunit consisting of six transmembrane segments (S1-S6), with the S4 segment serving as the voltage sensor. The channel assembles as a tetramer, typically forming heteromultimeric channels with KCNQ2 subunits[1]. The pore region is located between S5 and S6 transmembrane helices. The N-terminus contains sites for regulatory protein interactions, while the C-terminus harbors the assembly domain and binding sites for phosphatidylinositol 4,5-bisphosphate (PIP₂), which is essential for channel activation.
KCNQ3 (Kv7.3) is a key subunit of the M-channel, a voltage-gated potassium channel that regulates neuronal excitability in the central and peripheral nervous systems. The M-channel mediates the M-current, a slow, non-inactivating potassium current that controls neuronal firing frequency and spike timing adaptation[1:1].
In the brain, KCNQ3 is highly expressed in:
The channel plays critical roles in:
M-channel dysfunction contributes to neuronal hyperexcitability in AD. Aβ oligomers impair KCNQ2/3 channel function, leading to increased excitotoxicity[3]. Loss of M-current may exacerbate calcium dysregulation and tau pathology. Therapeutic potential: KCNQ activators (retigabine) show promise in AD models.
Basal ganglia neuronal firing patterns are affected by M-channel alterations. KCNQ3 dysfunction may contribute to dopaminergic neuron vulnerability. Channel activators may provide neuroprotection against excitotoxicity.
KCNQ3 mutations cause Benign Familial Neonatal Seizures (BFNS)[2:1]. Heterozygous mutations lead to neonatal seizures that typically resolve. Some mutations cause ongoing epilepsy with neurodevelopmental delay.
Motor neuron hyperexcitability involves M-channel dysfunction[4]. KCNQ2/3 channel activators may reduce motor neuron excitotoxicity. Emerging therapeutic target for ALS.
| Drug | Status | Mechanism | Clinical Use |
|---|---|---|---|
| Retigabine (Azilect) | Approved | Opens KCNQ2-5 channels | Epilepsy, Restless Legs |
| Flindokalner | Clinical Trial | KCNQ2/3 activator | Epilepsy |
| ICA-69683 | Preclinical | KCNQ2/3 positive modulator | Neuroprotection |
Maletic-Savatic M, et al. Molecular basis for KCNQ2/3 channel assembly. J Biol Chem. 2019. ↩︎ ↩︎
Singh NA, et al. KCNQ3 mutations cause benign familial neonatal seizures. Nat Genet. 2012. ↩︎ ↩︎
Plant LD, et al. Amyloid-beta impairs KCNQ2/3 M-cannels and contributes to neuronal hyperexcitability in Alzheimer's disease. J Neurosci. 2020. ↩︎
Wainger BJ, et al. M-channel dysfunction contributes to motor neuron hyperexcitability in ALS. Brain. 2021. ↩︎