sodium channel

sodium channel
(= sodium gate)
The protein responsible for electrical excitability of neurons. A multi-subunit transmembrane ion channel, containing an aqueous pore around 0.4nm diameter, with a negatively charged region internally (the "selectivity filter") to block passage of anions. The channel is voltage-gated: it opens in response to a small depolarization of the cell (usually caused by an approaching action potential), by a multistep process. Around 1000 sodium ions pass in the next millisecond, before the channel spontaneously closes (an event with single-step kinetics). The channel is then refractory to further depolarizations until returned to near the resting potential. There are around 100 channels per m m2 in unmyelinated axons; in myelinated axons, they are concentrated at the nodes of Ranvier. The sodium channel is the target of many of the deadliest neurotoxins.

Dictionary of molecular biology. 2004.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Sodium channel — Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell s plasma membrane.[1][2] They are classified according to the trigger that opens the channel for such ions, i.e. either a voltage… …   Wikipedia

  • Sodium channel blocker — Sodium channel blockers are agents used in the treatment of cardiac arrhythmia. They are classified as Type I in the Vaughan Williams classification.Antiarrhythmic The class I antiarrhythmic agents interfere with the (Na+) channel.Class I agents… …   Wikipedia

  • sodium channel blocker — sodium channel blocking agent …   Medical dictionary

  • sodium channel — a voltage gated channel selective for the passage of sodium ions; sodium channels are activated by membrane depolarization and are the main causes of depolarization and repolarization of the nerve membrane during the propagation of action… …   Medical dictionary

  • sodium channel blocking agent — any of a class of antiarrhythmic agents that prevent ectopic beats by acting on partially inactivated sodium channels to inhibit abnormal depolarizations …   Medical dictionary

  • Epithelial sodium channel — The epithelial sodium channel (short: ENaC, also: sodium channel non neuronal 1 (SCNN1) or amiloride sensitive sodium channel (ASSC)) is a membrane bound ion channel that is permeable for Li+ ions, protons and especially Na+ ions. It is a… …   Wikipedia

  • epithelial sodium channel — (ENaC) a non gated epithelial cell membrane channel through which sodium diffuses down its concentration gradient into the cell, leading to the absorption of water through water channels. Its functions include resorption of salt and water in… …   Medical dictionary

  • amiloride-sensitive sodium channel — epithelial sodium c …   Medical dictionary

  • Channel blocker — A channel blocker (CB) or ion channel blocker (ICB) is a type of drug which binds inside the pore of a specific type of ion channel and blocks the flow of ions through it, resulting in an alteration of the electrochemical gradient of the cell… …   Wikipedia

  • sodium-potassium ATPase — A major transport protein of the plasma membrane. A multi unit enzyme, it moves 3 sodium ions out of the cell, and 2 potassium ions in, for each ATP hydrolyzed. The sodium gradient established is used for several purposes (see facilitated… …   Dictionary of molecular biology

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”