Structure and diseases of ion channels 9-10-08

Structure and diseases of ion channels 9-10-08 - Structure...

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Unformatted text preview: Structure and diseases of Structure and diseases of ion channels ion channels Dr. McKemy 9/10/08 Topology of principal subunits of voltage-gated Na Topology of principal subunits of voltage-gated Na + and K and K + + channels channels Topology of voltage-gated Na Topology of voltage-gated Na + and K and K + channels channels K +-channels are tetrameric proteins. 6 transmembrane (S) domains and 1 P-segment. + S4 contains many (+)-charges residues. The voltage sensor . o The N-terminal domain is the inactivating segment. Na +-channels are monomeric proteins. Contain 4-homologous domains. + Each is structurally like the K +- channel subunits. Only one inactivating domain. + Between the III & IV transmembrane domains. The analogous S4 domains are the voltage sensors. Positively charged amino acids in the 4 Positively charged amino acids in the 4 th th transmembrane domain transmembrane domain How do these channels sense voltage? How do these channels sense voltage? Voltage-gated channels. Closed at resting MP. Depolarization opens these channels. + > depolarization, the > Na + influx. Structural changes that lead to gating. At rest, the cytosolic gate is closed. Depolarization is sensed by (+)-charged -helices. + Move towards the extracellular surface of the membrane. + Opens the gate. How do these channels sense voltage?...
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This note was uploaded on 11/02/2008 for the course BISC 421 taught by Professor Hirsch,liman,quick during the Fall '08 term at USC.

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Structure and diseases of ion channels 9-10-08 - Structure...

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