l6 Flashcards
what are the vesicles above the active zone anchored to the cytoskeleton by?`
Synapsin
what do ca2+ activate in the presynaptic button
CaMKII
what does CaMKII do
it phosphorylates synapsin, so p-synapsin can no longer bind to the cytoskeleton, allowing individual vesicles to dock onto the active zone
what complex docks the individual vesicles to the plasma membrane in the active zone
SNARE complex
At docking: what are the types of proteins
Synaptobrevin and synaptotagmin bound to the vesicle
Syntaxin and SNAP-25 at the membrane
They (except synaptotagmin) combine to FOrm SNARE complexes
What is the function of snare complexes
They pull the membranes together
what proteins do the calcium ions bind to at docking stage
Synaptotagmin
What does CA2+ bound synaptotagmin catalyse-
membrane fusion by binding to SNARE’s & plasma membrane
what is priming
Invoes partial assembly of SNARE complexes so docked vesicles are ready for fusion (to respond to ca2+)
what process re-forms the vesicles
Endocytosis recovers them, from the CSM
what do clostridal toxins do
cleave SNARE proteins
what does the Botulinum toxin do
Decreases neuromuscular transmission of ACH
acts directly at the neuromuscular junction. The muscles lose all input and so become permanently relaxed (treatment of muscle spasms).
what does Tetanus toxin do
inhibits the release of Glycine and GABA at inhibitory neurons, resulting in dis-inhibition of cholinergic neurons, which causes permanent muscle contraction.
Botox and tetanus both affect…
SNARE proteins
what does LEMS attack
Presynaptic CA2+ channels
what do cognitive disorders impair
Transynaptic signalling
Describe the action of Vesicular transporters powered by proton gradient
(can happen for all membrane transporters not just Glutamate and GABA-slide 14)
ATPase proton pump loads up vesicles with H+
making vesicles acidic
Plasma membrane transporters powered by electrochemical gradient
[Na+] higher outside / [K+] higher inside
Glutamate co-transported with 2 Na+
. 1 glutamate traded for 1 H+ (counter-transport mechanism
what function do glial cells have at the synapse when activated by neurotransmitter
They experience an increase in intracellular ca2+ and release tranmmitters of their own into the synapse to enhance or inhibit synaptic activity
what are the 4 main types of neurotransmitters
AA
monoamines
ACH
Neuropeptides
What are 3 key features that distinguish ACH and AA and amines from Neuropeptides
The first 3 are:Synthesized locally in presynaptic terminal
Stored in synaptic vesicles
Released in response to local increase in Ca2+
3 key features of neuropeptides
Synthesized in the cell soma and transported to the terminal
Stored in secretory granules
Released in response to global increase in Ca2+
give an example of a fat and slow neurotransmitter
Fast: AA
slow:neuropeptide
What is the theory behind why some neurotransmitters are fast and why others are slow
Fast transmitters (e.g. Glu) are stored in synaptic vesicles that are docked close to voltage-gated calcium channels in the membrane of the nerve terminal, and are released in a short burst when the membrane is depolarised. Slow transmitters (e.g. neuropeptides) are stored in separate vesicles further from the membrane. Release is slower, because they must first migrate to the membrane, and occurs only when [Ca2+] builds up sufficiently
give example s of AA transmitters that are excitatory and inhibitory
Excitatory : Glutamate (CNS)
Inhibitory: GABA (Brain)
Glycine (Spinal cord and brainstem)