Vandenberg_Lec8_2009

Vandenberg_Lec8_2009 - Structure & Function of...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Structure & Function of Voltage-gated Ion Channels 10/16/09 What are the actual structures of ion channels? How do channels detect a voltage change? Where is the activation gate that opens rapidly by depolarization? How does the inactivation gate close the channel? How do ions permeate the channel? How are channels selective for particular ions? Structure & Function of Ion Channels Tetrameric structure: 1 polypeptide 4 homologous domains Tetrameric structure: 4 separate polypeptides Is there a charged region of the channel that might be the voltage sensor? • Charges in the channel are proposed to move in response to membrane depolarization, and initiate a conformational change that opens the channel. • ~14 charges per channel move across the membrane
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 + Charged Amino Acids in S4 Segment of Voltage-gated Channels K: Na: Ca: Proposed that S4 is likely to be the voltage sensor S4 region proposed as voltage sensor. There are four S4 segments per channel X 4 subunits An early model for an S4 voltage sensor Depolarization: + charges repel S4 & push & twist it towards extracellular side + + + + + + + Models for Voltage Sensor: Horn (2005) Paddle model S4 Crevice model: Small movement of S4’s between aqueous crevices Translation model: Larger movement of S4’s across membrane
Background image of page 2
3 Voltage-sensing domains (red), composed of S1-S4, form distinct regions separate from the pore domain (S5-P-S6, blue). Overall structure is not compact—Voltage-sensing domain has extensive contact with lipid. The voltage-sensing domain from one subunit contacts the pore domain from the neighboring subunit. Top view: Side view: Structure of a mammalian Kv1.2 potassium channel Long et al, 2005, reviewed by Tombolo et al, 2005 How do the Voltage-gated Ion Channels Work? 1. What is the overall structure of the channels? The channel is a tetramer (K channels), or contains 4
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This document was uploaded on 10/21/2009.

Page1 / 9

Vandenberg_Lec8_2009 - Structure & Function of...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online