Review session 3 questions and answers

Review session 3 questions and answers - Review session 3...

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Review session 3 questions and answers 38. The plot below shows the averaged current of voltage-gated Na+ and K+ channels. a) What’s the direction of Na+ and K+ movements? Na current goes in to the cell. Since this is a positive ion going into the cell, it’s a negative current. K+ is a positive ion going out of the cell, hence a positive current. b) Why does the Na+ current go back to resting level faster than K+ current? Inactivation gate quickly blocks Na whereas K+ does not get inactivated. 39. How many transmembrane alpha-helixes does a voltage-gated Na+ channel protein subunit have? NaV has 4 subunits made up of 6 transmembrane alpha helices 40. In a voltage-gated Na+ channel, a) What part of the protein is responsible for ion selectivity? How? External loop connecting S5 and S6 lines pore, creating a selectivity filter similar to the K selectivity filter. b) What part of the protein is responsible for inactivation? How? Cytosolic loop connecting domain 3 and 4. Forms ball and chain which plugs the pore. c) Which segment is responsible for voltage sensitivity?
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This note was uploaded on 12/06/2011 for the course BIO 317 taught by Professor Simonhalegoua during the Spring '08 term at SUNY Stony Brook.

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Review session 3 questions and answers - Review session 3...

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