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Questions and Answers
What is the primary function of the Rab3 protein in neurotransmitter release?
What is the primary function of the Rab3 protein in neurotransmitter release?
- To target vesicles to active zones (correct)
- To anchor vesicles to the cytoskeleton
- To promote the recycling of vesicle membranes
- To facilitate vesicle fusion with the presynaptic membrane
During vesicle mobilization, what triggers the release of vesicles from synapsin binding?
During vesicle mobilization, what triggers the release of vesicles from synapsin binding?
- Calmodulin independent signaling
- Increase in synaptic vesicle volume
- Phosphorylation by PK-Ca2+/Calmodulin (correct)
- Depolarization without calcium influx
What role do the SNARE proteins play in neurotransmitter release?
What role do the SNARE proteins play in neurotransmitter release?
- Transporting vesicles along actin filaments
- Facilitating vesicle mobilization away from the active zone
- Anchoring vesicles to synaptic membranes and preparing for fusion (correct)
- Binding neurotransmitters before release
What is the significance of synaptotagmin in the process of neurotransmitter release?
What is the significance of synaptotagmin in the process of neurotransmitter release?
How is the fusion pore formed during the neurotransmitter release process?
How is the fusion pore formed during the neurotransmitter release process?
What step follows the exocytosis of vesicles in neurotransmitter release?
What step follows the exocytosis of vesicles in neurotransmitter release?
What initiates the process of vesicle mobilization in the presynaptic terminal?
What initiates the process of vesicle mobilization in the presynaptic terminal?
Which protein is responsible for the clathrin-mediated removal of the vesicular membrane after neurotransmitter release?
Which protein is responsible for the clathrin-mediated removal of the vesicular membrane after neurotransmitter release?
What is the primary role of the Rab3 protein in the process of neurotransmitter release?
What is the primary role of the Rab3 protein in the process of neurotransmitter release?
Which step in the neurotransmitter release process involves the interaction between the vesicle and the cytoskeleton?
Which step in the neurotransmitter release process involves the interaction between the vesicle and the cytoskeleton?
What is the primary function of the SNARE complex during neurotransmitter release?
What is the primary function of the SNARE complex during neurotransmitter release?
What role does synaptotagmin play during the process of neurotransmitter exocytosis?
What role does synaptotagmin play during the process of neurotransmitter exocytosis?
During the formation of a fusion pore, what primarily dictates the rate of neurotransmitter release?
During the formation of a fusion pore, what primarily dictates the rate of neurotransmitter release?
What triggers the transient formation of a fusion pore during neurotransmitter release?
What triggers the transient formation of a fusion pore during neurotransmitter release?
Which of the following best describes the all-or-nothing phenomenon of neurotransmitter release?
Which of the following best describes the all-or-nothing phenomenon of neurotransmitter release?
What is the consequence of spontaneous, low-frequency quantal release in the absence of action potentials?
What is the consequence of spontaneous, low-frequency quantal release in the absence of action potentials?
What role does Rab3 play in neurotransmitter release?
What role does Rab3 play in neurotransmitter release?
Which protein is considered the main v-SNARE involved in vesicle mobilization?
Which protein is considered the main v-SNARE involved in vesicle mobilization?
How do SNARE proteins engage in the priming process during neurotransmitter release?
How do SNARE proteins engage in the priming process during neurotransmitter release?
What triggers the fusion of the vesicle with the presynaptic membrane?
What triggers the fusion of the vesicle with the presynaptic membrane?
What is the primary function of t-SNARE proteins in neurotransmitter release?
What is the primary function of t-SNARE proteins in neurotransmitter release?
Which of the following proteins is not classified as a t-SNARE?
Which of the following proteins is not classified as a t-SNARE?
What mechanism describes the contact interaction between SNARE proteins?
What mechanism describes the contact interaction between SNARE proteins?
What role does synaptotagmin play in neurotransmitter release?
What role does synaptotagmin play in neurotransmitter release?
Study Notes
Mechanism of Neurotransmitter Release
- Initial influx of Ca2+ binds to synaptotagmin, inducing a conformational change that facilitates interaction with SNARE proteins.
- SNARE proteins (v-SNARE and t-SNARE) bring synaptic vesicles close to the presynaptic membrane, preparing for neurotransmitter release.
Vesicular Stages in Release Process
- Mobilization: Phosphorylation of synapsin releases vesicles bound to cytoskeleton (actin filaments), allowing movement towards active zones.
- Traffic: Vesicles are targeted to active zones through G proteins, including Rab3 (vesicular) and Rim (membrane).
- Docking & Priming: Vesicles are anchored at active zones via SNARE complex, consisting of synaptobrevin (v-SNARE), syntaxin, and SNAP-25 (t-SNARE).
Fusion Process
- Fusion: Ca2+ binding to synaptotagmin facilitates vesicle fusion with presynaptic membrane, creating a fusion pore.
- This process results in neurotransmitter release through exocytosis, driven by the significant increase in intracellular Ca2+ during action potential (AP).
Neurotransmitter Characteristics
- Synaptic vesicles serve as storage organelles for neurotransmitter quanta; release is all-or-nothing and depends on Ca2+ influx.
- Each vesicle represents one quantum of neurotransmitter; for example, one vesicle contains approximately 5,000 molecules of acetylcholine (ACh).
Action Potential Influence
- In absence of AP, a low-frequency spontaneous quantal release occurs (~1 quantum/sec), while AP increases the release rate by over 100,000 times, leading to ~150 quanta/msec.
Exocytosis and Fusion Pore Dynamics
- Exocytosis is facilitated by a transient fusion pore formed between vesicular and presynaptic membranes.
- Ca2+ promotes the opening and dilation of fusion pores for effective neurotransmitter release.
Summary of Release Steps
- Steps involved in neurotransmitter release include:
- Release from cytoskeleton interaction
- Targeting and anchoring to active zones of the plasma membrane
- Preparation for fusion (priming)
- Fusion with the presynaptic membrane
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Description
This quiz explores the role of calcium ions (Ca2+) in neuronal signaling, particularly how Ca2+ interacts with synaptotagmin and the SNARE proteins during synaptic transmission. Test your understanding of the mechanisms underlying neurotransmitter release and synaptic functioning in the nervous system.
