1: Toxins

Question 0

Beta Bungarotoxin

Answer 0

Localises to membrane via potassium moiety

Blocks acetylcholine release through phospholipase A2 activity

Question 1

Alpha Bungarotoxin

Answer 1

Irreversibly blocks n.m.j.

Does not block ganglions

Question 2

Botulinum toxins

A B C1 D E F G

Answer 2

C terminus -> ganglioside receptor
N terminus translocates with light chain through a channel
Light chain has peptidase activity and cleaves the snare protein, blocking acetylcholine release
A & E - SNAP25
BDFG- synaptobrevin
C1- Syntaxin and SNAP25

Question 3

Tetanus Toxin

Answer 3

Retrograde transport to cell body

Inhibits inhibitory neurone by cleaving synaptobrevin

Question 4

D Tubocurarine

Answer 4

Non selective AChR blocker (both ganglionic and nmj)

Question 5

Hemicholinium

Answer 5

Blocks choline uptake via the sodium-choline cotransporter, SLC5A7
This is the rate limiting step in ACh synthesis

Question 6

Alpha latrotoxin

Answer 6

Binds to neurexins on plasma membrane and causes mass release of ACh by forming calcium permeable channels.
Can also inhibit potassium channels.
Black widow spider toxin