General properties of ion channels

Question 1

K+ channel structure

Answer 1

1, structure of an inverted teepee: 4 subunits each has 6 transmembrane helices

2. two of the transmembrane helices sperated by P loop that lines the pores and control the channel’s specificity for K+
3. gate on ic side
4. ec side: selectivity filter that forms a bottle neck for the ion
5. K+ only can be in 4 specific position, 2 at a time, either 1 3 or 2 4, surrounded by water molecule
6. in the binding site: 8 carbony oxygen
7. transition state: 4 carbonyl oxygen and 2 water molecule -> low energy barrier

Sodium doesnt have the binding ability because the oxygen shell too big

Question 2

ion channel

Answer 2

1. process several open and clsoed state

Question 3

rate constant

Answer 3

probably of transition among open and closed state

voltage and ligand affect gating by altering the rate constant (which open probability is a function of)

Question 4

gating scheme

Answer 4

describe kinetics and whole cell ionic current

Question 5

throughput

Answer 5

the amount of ion that passes through a gate at a given time

Question 6

theoretical max diffusion

Answer 6

highest diffusion possible through same size permable membrane