What is ENaC biology?
The epithelial sodium channel (short: ENaC, also: amiloride-sensitive sodium channel) is a membrane-bound ion channel that is selectively permeable to the ions of sodium (Na +) and that is assembled as a heterotrimer composed of three homologous subunits α or δ, β, and γ, These subunits are encoded by four genes: …
What is ENaC channel kidney?
Overview: Epithelial sodium channels (ENaC) are responsible for sodium reabsorption by the epithelia lining the distal part of the kidney tubule and fulfil similar functional roles in some other tissues such as the airways and the distal colon.
How is ENaC activated?
Furin-mediated cleavage of α-ENaC activates ENaC by releasing an inhibitory peptide from the ECL. Furin-dependent proteolysis of α-ENaC activates the channel by relieving Na+ self-inhibition (see Intrinsic Factors below), thereby increasing Na+ transport at higher extracellular Na+ concentrations.
What is the action of aldosterone on the kidneys?
Aldosterone causes an increase in salt and water reabsorption into the bloodstream from the kidney thereby increasing the blood volume, restoring salt levels and blood pressure.
What is normal range for aldosterone?
Contact your healthcare worker if you have any questions. The following are considered to be normal results for this test: Adults: Supine, normal-sodium diet: 2-9 ng/dL (55-250 pmol/L) [5]
What is the mechanism of action of ENaC?
The activity of ENaC in the colon and kidney is modulated by the mineralcorticoid aldosterone. It can be blocked by either triamterene or amiloride, which are used medically to serve as diuretics.
Where is ENaC expressed in the skin?
In the skin epidermal layers, ENaC is expressed in the keratinocytes, sebaceous glands, and smooth muscle cells. In these cells ENaC is mostly located in the cytoplasm. In the eccrine sweat glands, ENaC is predominantly located in the apical membrane facing the lumen of the sweat ducts.
What is The cryoEM structure of ENaC?
The cryoEM structure of ENaC indicates that the channel is a heterotrimeric protein like the acid-sensing ion channel 1 (ASIC1), which belongs to the same family. Each of the subunits consists of two transmembrane helices and an extracellular loop. The amino- and carboxy-termini of all three polypeptides are located in the cytosol .
What is the role of ENaC in cystic fibrosis?
ENaC interaction with CFTR is of important pathophysiological relevance in cystic fibrosis. CFTR is a transmembrane channel responsible for chloride transport and defects in this protein cause cystic fibrosis, partly through upregulation of the ENaC channel in the absence of functional CFTR.