Ion Channels Flashcards Preview

Neurobiology > Ion Channels > Flashcards

Flashcards in Ion Channels Deck (37):
1

Ion Channels

Integral proteins that span the cell membrane and form conduits for ions to pass through the lipid bilayer

2

Ion Channel Properties

Selective
Open and close in response to signals
Conduct ions at rapid rates

3

Voltage gated ion channels

Respond to changes in membrane potential

4

Ligand gated ion channels

Respond to chemical transmitters

5

Mechanically gated ion channels

Respond to pressure or stretch

6

Cation

Positive ion

7

Anion

Negative ion

8

Exchanger

Can use the energy stored in conc. gradient of one ion to transport another ion against its conc. gradient

9

Hetero-oligomers

5 different subunits

10

Homooligomers

6 subunits are the same

11

Single polypeptide chain

Organized into 4 repeating motifs

12

Smaller ions have a hydrated diameter that is..

Larger than that of larger ions

13

Selectivity Filter

High negative site that allows na+ to pass through but not K+

14

Localized conformational change

Ion channel only changes in one spot

15

Generalized structural change

Ion Channel changes all along the channel

16

Blocking Particle change

Blocking particle swings into and out of the channel mouth

17

Laws of electrodiffusion

Laws of binding of ions to specific amino acids along the pore of an ion channel

18

IV Curve

Rate of flow of current

19

Dissociation constant

The ligand concentration at which current reaches 1/2 of its max value

20

Simple resistors

Linear
Conducts ions in a constant manner at all voltages

21

Rectifying Channel

Non-linear
Conducts ions more readily in one direction than the other

22

Superfamilies

Ligand Gated Channel
Gap-Junction Channel
Voltage-Gated Channel

23

Ligand Gated Channel Superfamily

5 subunits
4 transmembrane helixes each

24

Gap-Junction Channel Superfamily

One pair of hemichannels
Each hemichannel has 6 identical subunits
Each subunit contains 4 alpha helixes

25

Voltage Gated Channel Superfamily

Single Polypeptide chain
4 homologous motifs
Each motif has 6 alpha helixes
S5-S6 strand is P loop (Selectivity Filter)

26

Ion Channel Families with P regions

Voltage gated K+ channel
Inward-Rectifying K+ channel
K+ channel with 2 P regions
Glutamate receptor channels

27

Voltage Gated K+ Family

Four subunits
Each subunit has 6 transmembrane segments
Each subunit has a pore forming P-region

28

Inward Rectifying K+ channels Family

Four subunits
Each subunit has 2 transmembrane segments
Transmembrane segments connected by a P region

29

K+ channel with 2 P regions Family

2-4 subunits
4 transmembrane segments
2 pore forming P regions

30

Glutamate receptor channel family

P region enters and exits on the cytoplasmic side of the membrane
4 subunits
2 transmembrane segments

31

High energetic cost of K+ ions to enter bilayer is minimized by...

1. Inner chamber filled with polar water
2. 4 helixes provide dipole whose negative charge points toward inner chamber

32

Ions in outer configuration

Positions 1 and 3

33

Ions in inner configuration

Positions 2 and 4

34

Chloride Channels

2 identical subunits each forming a selective Cl- pore
18 alpha helixes
Move Cl- against concentration gradient using H+ gradient

35

Myotonia

Abnormal prolonged muscle contraction

36

K+ channel selectivity filter

Parallel (Barrel Stave)

37

Cl- channel selectivity filter

Anti-parallel