Vesicular transmitter release II Flashcards
Vesicle fusion?
active fusion of the vesicle membrane with the plasma membrane to release vesicular contents when the local calcium reaches a threshold level
Which vesicles fuse once the local calcium level crosses a threshold?
Primed vesicles
Vesicular recycling?
Recycling - of vesicular membrane by endocytosis to form a new vesicle for transmitter filling
Why do small molecules have to be synthesised in the nerve terminal?
Vesicles only operate in the nerve terminal
Role of VAMP/synaptobrevin?
synaptic vesicle protein, central to vesicle fusion regulation
Role of Synaptotagmin?
part of the control machinery involved in triggering of fusion event
Use of SV2s, SCAMPs, synaptogyrin?
ID vesicles experimentally
promoters to drive expression of smthn in a nerve termina
Why are SV2s, SCAMPs, synaptogyrin used as promoters?
They are ve selective to nerve terminal machinery and processes
What type of molecule are RABs?
Small GTPases
Role of RAB3?
involved in early docking and binding events
Active form of RAB3?
GTP bound
What does active (GTP bound) RAB3 bind to?
RIM plasma membrane protein
What does RAB3 do after binding to RIM?
Form a scaffold w/ Munc13, rabphillin and calcium channels
RAB3 involved scaffold?
Ensures docking of the vesicle is close to the sensing machinery–> vesicle is close to site of calcium channel
What are C2 domains?
Calcium and lipid binding domain
Where are C2 domains often found?
Proteins involved in membrane signalling events
What do fusion events require?
An N-ethylmaleimide (NEM) sensitive factor, called NSF
What does the NEM sensitive factor have a requriement for?
ATP
How were the proteins that associate with the NEM sensitive factor determined?
Affinity column processes–> NEM factor on a column, pass homogenate down the columns and see which proteins are pulled out
What does SNAPs stand for?
Soluble NSF attachment proteins
What does SNAREs stand for?
Soluble NSF attachment protein receptors
Role of SNAREs?
Associate together to regulate vesicle fusion events
Where does the VAMP part of the SNARE complex sit?
Vesicular membrane
Where does the remaining (non-VAMP) proteins of the SNARE complex attach?
Recipient plasma membrane
What is the SNARE complex?
A complex between the proteins on the vesicular membrane and the plasma membrane
tSNAREs (targetSNAREs)?
Syntaxin I, SNAP25
Syntaxin I?
Presynaptic plasma membrane protein (integral)
SNAP25?
Presynaptic plasma membrane protein (anchored)
vSNARE (vesicularSNAREs)?
Synaptobrevin
Synaptobrevin?
Vesicular membrane protein (integral)
What is the structure of a synaptic SNARE complex?
four parallel helices
Which molecules contribute to the four parallel helices in a synaptic SNARE?
Syntaxin and synaptobrevin contribute oen motif each, SNAP25 contributes two motifs
Which toxins can affect proteins in the SNARE complex?
Botulinum toxin, tetanus toxin, clostridium toxin
