Resting ion channel

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Resting channels are ion channels in the plasma membrane of a cell that remain open at all times. Also called leakage channels or leak channels, resting channels allow ions to cross the membrane down their electrochemical gradient whether or not the cell is depolarized. This is in contrast to gated channels which may be either voltage-gated, ligand-gated, or stretch-gated. Unlike gated channels, which have two or three conformational states (resting, active, and sometimes inactivated), resting channels have only the open state.

In neurons, resting channels contribute to the negative resting membrane potential in by allowing positively-charged potassium ions to flow out of and negatively-charged chloride ions to flow in to the cell down their electrochemical gradients. Since there are fewer resting sodium channels than there are resting potassium and chloride channels, this causes a net efflux of positive charge, making the resting membrane potential hyperpolarized, or negative. This continuous flow of ions is known as a "leak current". Leak currents are much smaller than currents flowing through voltage-gated ion channels.

Resting potassium channels are thought to lack the S4 voltage-sensing region (discussed in the article on sodium channels) which confers the ability to change configuration in response to changes in transmembrane potential.^[1]

[edit] References

^ Karp G. 2005. Cell and Molecular Biology: Concepts and Experiments, Fourth ed, p. 167. John Wiley and Sons, Hoboken, NJ.

Hille, B. 2001. Ion Channels of Excitable Membranes, Third ed. Sinauer, Sunderland, MA.
Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed., pp.106, 129-131. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6