Flashcards in Lecture 19 Deck (23):
Describe the cycle of vesicle (docking on).
Docked at plasma membrane
Primed with ATP
Ca triggered fusion & exocytosis
May/may not collapse
Clatherin mediated endocytosis
ATPase NT reloading
May/may not fuse with endosome
What are the three levels of vesicle pools?
Readily releasable pool = RRP = at membrane ready for release
When not in use, where are extra vesicles in the cell (either as part of recycling or reserve pool)?
Tethered to actin cytoskeleton via synapsin
What must happen to allow for vesicle recycling from the membrane?
Ca2+ cleared and original state restored
How does Ca-mediated fusion occur? (mechanism)
T-snares + V-snares
Pair --> docking --> zipper
How does vesicle snare dissociation occur?
How many alpha helices are in the T/V snare combo complex?
What are 2 noteworthy T-snares?
Both in the target membrane
What is a noteworthy V snare?
What makes snare fusion Ca sensitive?
Synaptotagmin = on vesicle
"TAG into the complex"
2 C2 domains - together bind 5 Ca molecules
Binds the SNARE complex AFTER it has assembled to bring the vesicle to the plasma membrane
When active - binds the target plasma membrane, Ca binding makes it pull the 2 membranes closer together
What happens if you knock out synaptotagmin?
No fast vesicle release
What are some toxins that affect presynaptic release?
Tetanus - cleaves VAMP
Botox (botulinum toxin) - 3 types cleave each of the 3 V/T
What is the glutamate receptor? What ions move through the receptor?
Is glutamate excitatory or inhibitory?
Excitatory - EPSP - makes sense because cations move through the receptor into the cell!
How is glutamate cleared from the cleft to terminate neurotransmission?
What type of post-synaptic receptor gives a fast response?
Receptors that are ion channels
What determines the excitatory effect of a receptor channel?
Its reversal potential
Do the characteristics of a single or group of channels dictate EPSP kinetics?
Single channel properties - makes sense because a single channel is the building block!
What ions flow through inhibitory synapses?
Cl = short circuits membrane
K = hyperpolarization
Where are inhibitory synapses usually located on the neuron? 3 locations.
Post synapse @ soma or axon initial segment
ALL STRONG SITES FOR INHIBITION
(Mechanism next lecture: lets excitatory signals leak out at critical junctures)
What signals do inhibitory synapses create?
IPSPs - hyperpolarize the cell
What are the 2 main inhibitory NTs? Where do they act?
Glycine = spinal cord
GABA = brain