Vesicular transmitter release I Flashcards
What is neurotransmitter release a specialised form of?
Membrane fusion
Why is high spatial and temporal resolution needed for NT release?
Ensure it is controlled in terms of release of vesicles into the correct parts of the neurons/synapse, and at the right pace so the AP can be moved forward
What are quanta?
Small defined packets of NT
What is the release of NT triggered by?
Calcium mediated fusion events
What did Katz discover?
NT release occurs in integers–> multiples of a packet, called a quantum
What did Katz show regarding one vesicle?
It produced a potential of ab 0.5mV
Two types of vesicle?
Small synaptic vesicles, Large Dense Core Vesicles
SSV diameter?
50nm
What is found in SSVs?
Small molecule transmitters
Examples of NTs packaged into SSVs/
GABA, dopamine, ACh, glutamate
How was it discovered that vesicles are recycled?
If not the nerve terminal membrane would keep expanding as vesicles fused with it
Where are vesicles recycled?
nerve terminal–> presynaptic bouton
LDCV diameter?
250nm
What are found in LDCV?
Neuropeptides
What are neuropeptides dependent on?
AA translation
Where are LDCVs filled?
Cell soma
Why are LDCVs v electrodense/dark?
Contain a lot of peptide
What is present in a LDCV other than neuropeptides?
Enzymatic machinery used to process the peptides
What is the postsynaptic ensity?
A proteinaceous (protein rich) part of the synapse
Reflects sensing machinery that controls synaptic level signalling
Reserve pool?
vesicles that are sitting away from the membrane
Docked vesicles?
Vesicles which are primed and “ready to go” at the nerve terminal membrane
Will immediately fuse upon depolarization
Differences between synapses?
Number of vesicles, rate of release, amount of molecule per vesicle
Calyx of Held
Large synapses–> 300 vesicles per ms
Retinal and inner ear synapse release rate?
1000s vesicles per ms
Fast cerebellar connections release rate?
3 vesicles per ms
Why is it difficult to study some neurons under culture?
They release v few vesicles upon depolarisation
Stages of transmitter release?
Loading, docking, priming, fusion, recycling
Vesicle docking?
membrane of vesicle tightly associates with plasma membrane of the nerve terminal
Vesicle priming?
creation of a competent readily releasable pool of vesicles
What are vesicles in the reserve pool tethered to?
Cytoskeleton
How are reserve vesicles recrutied?
Ca2+
