Sodium channel protein type 7 subunit alpha is a protein that in humans is encoded by the SCN7Agene on the chromosome specifically located at 2q21-23 chromosome site. This is one of 10 Sodium channel types, and is expressed in the heart, the uterus and in glial cells. Its sequence identity is 48, and it is the only sodium channel known to be completely un-blockable by TTX (tetrodotoxin).
Scn7a is the name of the gene that encodes to a membrane protein, in particular a Sodium Channel Nax (also known as NaG, Nav2.1, etc.) It belongs to a family of Sodium Channel known as Voltage-Gated, but is not activated by changes in the membrane's voltage, as happen usually in the members of this family (Nav1.1 to Nav1.9); it activates by changes in the extracellular concentration of sodium [~150 mM].
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