Structure and Modulation of Voltage-Gated Sodium Channels
The depolarizing phase of the action potential in most excitable cells results from an initial increase in sodium permeability mediated by voltage-gated sodium channels followed by a more prolonged increase in calcium permeability mediated by voltage-gated calcium channels. Repolarization is then caused by activation of voltage-gated potassium channels. Calcium entering the cell during the action potential serves as an intracellular messenger to initiate secretion, contraction, and metabolic and regulatory events. The voltage-gated ion channels are also subject to regulation by interaction with G proteins and by protein phosphorylation stimulated by intracellular second messengers. This form of ion channel modulation has been reported for many calcium channels and potassium channels, but has been described less frequently for sodium channels. In this brief chapter, we have reviewed research from our laboratory which has given new insight into the molecular properties of sodium channels and the molecular basis oftheir modulation by cAMP-dependent protein kinase and protein kinase C.
KeywordsSodium Channel Complex Of320 Channel Inactivation Scorpion Toxin Sodium Channel Activity
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