PHIL 2015 Lecture Notes - Lecture 49: Central Nervous System, Potassium Channel, Peripheral Nervous System
23 May 2020
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Document Summary
Nav1. 1, 1. 2, 1. 3 and 1. 6 are mainly expressed in the central nervous system (cns) Nav1. 7, 1. 8 and 1. 9 are expressed in peripheral nervous system (targets for pain) Nav1. 4 and 1. 5 isoforms are present in adult skeletal muscle and heart muscle, respectively. The ion selectivity filter has a high-field-strength site at its extracellular end, formed by four glutamate residues-create a high local electric fieldstrength as a cation coordination site, and an energetic barrier to anion permeation. These are key determinants of ion selectivity in both vertebrate sodium and calcium channels. The filter of this channel is relatively short. The central cavity is large enough to contain a sodium ion with its first hydration shell, and rapid diffusion is facilitated by a hydrophobic surface. Voltage sensing domain-during depolarization, the s4 segment moves outward toward a spiral path and initiates the conformation change that opens the pore. This is similar to a sliding helix model of voltage sensor function(check diagram on slide 13)
