SCN7A
Description
The SCN7A (sodium voltage-gated channel alpha subunit 7) is a protein-coding gene located on chromosome 2.
SCN7A, also known as the Nax channel, is a sodium channel alpha subunit expressed in the heart, uterus, and glial cells of mice. It has a low similarity to other known sodium channel alpha subunits. While scientists have not yet been able to create a functional voltage-gated channel from SCN7A, two theories exist regarding its purpose: a sodium sensor and an ion channel. In mice, SCN7A acts as a sodium sensor, activated by changes in extracellular sodium concentration, and plays a role in regulating sodium levels. Scn7a knockout mice show altered responses to sodium intake and dehydration. SCN7A is found on sympathetic neurons and might be important for these responses. In humans, SCN7A is proposed to function as an ion channel, but this has not been confirmed.
SCN7A acts as a sodium leak channel, serving as an osmosensor that regulates sodium ion levels across various tissues and organs. Unlike most sodium channels, SCN7A is not voltage-gated, allowing sodium to flow passively through the cell membrane along its concentration gradient. In glial cells of the central nervous system, SCN7A detects changes in body fluid sodium levels and regulates salt intake behavior and voluntary water consumption. It achieves this by activating nearby neurons, ensuring appropriate sodium levels within the body. Additionally, SCN7A plays a role in maintaining skin barrier homeostasis by mediating sodium influx into keratinocytes. The sodium channel formed by SCN7A is likely a heterooligomeric complex composed of the pore-forming alpha subunit (SCN7A) and regulatory beta subunits, such as SCN3B. SCN7A interacts with ATP1A1, activating it and indirectly signaling to nearby neurons to maintain sodium homeostasis.
SCN7A is also known as NaG, Nav2.1, Nav2.2, SCN6A.
