Target type: molecularfunction
Enables the transmembrane transfer of a sodium ion by a channel that opens when a specific ligand has been bound by the channel complex or one of its constituent parts. [GOC:mah]
Ligand-gated sodium channel activity is a fundamental process in cellular signaling, particularly in the nervous system. It involves the rapid influx of sodium ions (Na+) into a cell through a transmembrane protein channel, triggered by the binding of a specific ligand molecule. These channels are typically composed of multiple subunits, each with distinct domains responsible for ligand binding, ion permeation, and channel gating.
When a ligand binds to its specific site on the channel protein, it initiates a conformational change, causing the channel to open. This opening allows Na+ ions to flow down their electrochemical gradient, moving from the extracellular space into the cell's cytoplasm. This influx of positive charge creates a transient depolarization of the cell membrane, which is essential for the propagation of action potentials, the electrical signals that transmit information throughout the nervous system.
The speed and specificity of ligand-gated sodium channel activity are critical for precise and rapid neuronal signaling. These channels are involved in a wide range of physiological processes, including:
* **Neurotransmission:** Ligand-gated sodium channels mediate the rapid depolarization of postsynaptic neurons, triggering neurotransmitter release and propagating the signal to the next neuron.
* **Muscle contraction:** In skeletal muscle, acetylcholine binding to nicotinic acetylcholine receptors (nAChRs), a type of ligand-gated sodium channel, initiates muscle contraction.
* **Sensory perception:** Ligand-gated sodium channels are involved in sensory perception, such as taste, smell, and touch, by translating sensory stimuli into electrical signals.
The diverse functions of ligand-gated sodium channels highlight their crucial role in maintaining neuronal activity and overall physiological function. Dysregulation of these channels can lead to a variety of neurological disorders, including epilepsy, Alzheimer's disease, and Parkinson's disease.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Acid-sensing ion channel 3 | An acid-sensing ion channel 3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UHC3] | Homo sapiens (human) |
| Amiloride-sensitive sodium channel subunit alpha | An amiloride-sensitive sodium channel subunit alpha that is encoded in the genome of human. [PRO:DNx, UniProtKB:P37088] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| amiloride | amiloride : A member of the class of pyrazines resulting from the formal monoacylation of guanidine with the carboxy group of 3,5-diamino-6-chloropyrazine-2-carboxylic acid. Amiloride: A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705) | aromatic amine; guanidines; organochlorine compound; pyrazines | diuretic; sodium channel blocker |
| benzamil | guanidines; pyrazines | ||
| phenylamil | phenylamil: irreversible inhibitor of sodium channels in the toad urinary bladder | guanidines; pyrazines |