Cell M2: Module 3 Flashcards
spontanrous chanes in muscle membrane potential in the absense of motor nerve stimulation
miniture end plate potential mEPPs
what was used to study NT release through exocytosis
neuromusclar junctions NMJs
what end plate potentials
stimulation of motor nerve generates
what ofte elcits an action potential in muscle
end plate potentials
the larger the depolarisatio of the cell membnrane the ____ openings of Ca 2+ voltage gated channels
more
what does the presynaptic injection of Ca2+ chealtors do
eliminates post synaptic potentials by blocking NT release
what are chelators
naturally occuring bind inhibitors
presynaptic injection of Ca2+ leads to
PSP - post synaptic potentials
what accounts for most of synaptic delay during membraane depolarization
delayed opening of Voltage gated calcium channels
neuropeptides
small peptides that are neurotrnamsittes
where are neuropeptides synthesized
in the soma from precursors at the endoplasmic reticulum to the golgi
do neuropeptides undergo reuptake
no, broken down by proteolytic enzymes
how are neurotransmitters trnasported into synaptic vesicles
agaisnt electrochemical gradient, using energy from vescular proton pump
compensart endocytosis menaing
plasma membrane needs to be held at constant material, so excocytosis of 1 = endocytosus of 1
how long does process from exocytossis to ready for endocytosis take
10-20 seconds
how long does a whole cycle of becoming ready for exocytosis to just being endocytosed takes
1 minutes
do all vesicules need to go thorgh endosomes?
not the recylcyed ones, the immeduate become synaptic vesicles
the recyling pool of SV is ___% big
20%
what is required for SV primin
SNARE proteins which form a SNARE complex
how does a SNARE complex work
a snare complex brings the - charged membranes together for fusion
synaptic vesicle exocytosis is mediated by
syntaxin
SNAP25
synaptobrevin
redily reusable pool of all SVs at CNS synapses is ___ % or ___ vseicles
2-4 % or 5-10 vesicles
why are some vesicles in recycling pool not readily reusable
they are availible for release after initial sitmulation
what happens to syntaxin, snap 25 and synaptobrvin to requrie enegery to bring negatively charged membrnes together
theyr alpha helices intertwined in coiled mess that produces energy
_______ is responsible for tetanus and botulism neurotoxins and ar ehighly specific proteases that block NT release by cleaning SNARES
clostridial neurotoxins
what blocks NT release by cleaving snares
clostridial neurotoxins
____ sped up the fusion of lysosomes with each other and are essential for evoked and spontatnrou NT reoease
Munc 18 proteins
possible functions of Munc18 protein
1) bind to snare compares and unfold it so it can interact with other snares
2) may bind to snare complex and facilitate complex mediate fuision directily
the chaperon protein that unwinds SNARE complexes
NSF and Aplha SNAP
NSF that uses ATP to bind to alpha SNAP that binds to SNARE complex
unwind to individuals to use again/ recycle
what happens if we run out of NSF proteins
run out of SNARE protiens for Sv fusion. The synthesis of SNARE proteins is not enough on their own
integra; SV membrane protein associated with SNARE compex; calcium sensor
synaptotagmin
synaptotagmin 1 is needed for what
only for action-potential evoked fast synchronised NT release
what does synaptotagmin bind calcium with
2 cytoplasmic regions of protein
filamentoud material that surrounds the docked synaptic vesicles and provides docking sites for Sv; recruits calcium channels nd provides cell adhesion
active zone cytomatrix
a family of presynaptuc cell adhesion proteins
neurexins
CASK and PSD95 are both
scaffolding proteins
neurexins are impolicated in what kind of disorders
neurodevelopmental disorders sucha s autism
molecular scaffolding components that tether SVs to cytomatric with Rab 3 protein
RIM protein
functions of RIM protein
recruitment of Ca channels
suppoert sSV priming with Munc 13
ther SV to active matrix with Rab 3
scaffolding protein that faciliatates priming and interacts with components of the SNARE complex
Munc 13
what activates munc 13 and thus facilitates priming
calcium and diaglycerol
what would happen if munc 13 not present in synapses
synaptic neurotrnasmitter transmission abolished
explain nucleation
the assembly of a clathrin lattic on membrane to be endocytosed
explain invagination
generates clathrin coated pits/ puches
explain fission
the superation go membran pouch from membrane using dynamin
uncoating is what
the dissasembly of the clarithin-coat
what proteins are neede for clathrin to start the lattace
AP2 and AP180
structure of clatherin that helps keep the lattice from seperatinng
trisklion structure and epsin (curved)
how does dynamin tighten during fission
GTP bound energy - GTP hydrolysis
chaperon protein that uncoats che vesicle
Hsc 70 which needs adaptor protein auxilin to first bind to the lattice
proteins that modulate SV recylcing
actin
synapsin
what happens if synapsins are phosphorylated
they can no longer bind to things, CAMKII and PKA do this
why is there sometimes no action potential elicited in post synaptic specialization even tho there was one presynaptically
no snaptic vesicle fusion with plasma membrane so there was no neurotransmitter relase
what determines teh size of the readily realeasable pool of SVs
# of SVs that can dock at active zone fraction of docked Svs that are primed
residual calcium does what
increases SV docking
accelerates Sv rpiming
facilitates SV fission
