Modulation of ion channel activities that regulate transmitter secretion Flashcards
Describe an Action Potential
• When membrane potential is at rest both Na and K channels are closed
Desribe synaptic transmission
• An AP invades a presynaptic terminal
What are the diff types of ion channels
Voltage-gated ion channels
Desribe presynaptic ion chanel arrengenment
There are a number of diff ion channels tht are found on the presynaptic ion channel that can affect and result in changed in NM release
List the diff Voltage gated ion channels
Calcium channels
Describe the general structural topology of voltage gated ion channels
• There is the alpha subunit on the Ca channel; it consists of 4 domains and 6 transmembrane domains, and there is a little pore loop found between transmembrane domains 5 and 6
Describe presynaptic Calcium channels
• Ca enters through presynaptic voltage-gated Ca channels and initiates the release of neurotransmitters.
How do the various Ca binding proteins modulate Ca channels?
• CBD and IM modulate the function of Ca channels
Describe the alpha 1 subunit
• The a1 subunit incorporates the conduction pore, the voltage sensors and gating apparatus, and most of the known sites of channel regulation by second messengers drugs and toxins
Describe the synprimt site
SNARE proteins syntaxin 1A and SNAP 25 interact with the Ca channels by binding to the intracellular loop between domains II and III of the a1-subunit.
What happens when synprint peptides are present
• When synprint peptides are applied they prevent the SNARE proteins from binding to Ca channels
Presynaptic Ca channels
• The beta gamma subunit of G protein-coupled receptors can bind to these Ca channels and they can have a negative effect on these channels
Potassium channels are crucial regualtors of
- Neuronal excitability
Where can K channels be found
They can be found in a number of places like the neuronal dendrites, axons, soma, and presynaptic channels
What are the three categories of K channels and how do they affect neurotransmitter release?
• Low voltage-activated K Channels
What happens if we block any of the three K channels?
• If we block low voltage-gated K channels we start seeing aberrant AP firing leading to more neurotransmitter release
Descirbe Sodium channels
• The primary role of sodium channels is to generate action potential
What are the 5 post transcriptional modifications
- RNA editing
How do translational repressors affect the affect Na channels?
We have a translation repressor that can a bind to mRNA of Na channels repressing translation resulting in fewer fucntional Na channels expressed on the membrane
List the diff short term synaptic plasticity
Facilitaiton
Describe Facilitaiotn and depression when looking crayfish neuromuscular juncution
• There are two types of motor neurons phasic and tonic
Descirbe facilitation, depression, and augmentaiton with PTP
• In facilitation the NM release goes up while stimulating; when we stop stimulation it goes back to the baseline
What are some proposed mechanisms for facilition
• The residual Ca hypothesis
The residual Ca hypothesis
• When two AP occur in a short time
Residual Ca binds to a facilitator sensor
• AP and Ca enters the presynaptic temrial and binds to syanototagmin and triggers NM release
Spike broadening: inactivation of K channels
• Synaptotagmin on the synaptic vesicle
Calcium current facilitation
• Ca binding proteins can effect ca channel function
Ca current facilitation and (IM) site
• If we have two AP we get an increase in Ca current in response to second AP
Buffer saturation
• Ca buffer are Ca binding proteins
