Module 9.2: Regulated Secretion - Classical Neurotransmitters vs Neuropeptides

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Questions and Answers

What is the key factor for sorting neuropeptides into Dense Core Vesicles (DCVs)?

G-protein-gated receptors

Transporters

Synaptic vesicles

Aggregation and timing of cleavage (correct)

What is the key factor for sorting classical transmitters into synaptic vesicles?

G-protein-gated receptors

Neuropeptides

Aggregation and timing of cleavage

Transporters (correct)

What type of receptors do neuropeptides use for transmission?

Transporters

G-protein-gated receptors (correct)

Synaptic vesicles

Active Zone vesicles

Where are classical transmitters synthesized before being packaged into synaptic vesicles?

Cytoplasm (B) Signup and view all the answers

What is the major difference between 'classical' and peptide transmitters in neurons?

How they are made and how they get into vesicles (B) Signup and view all the answers

What is the function of G-protein-gated receptors in neuropeptide transmission?

Initiating second messengers and slow channels (D) Signup and view all the answers

What is the role of Dense Core Vesicles (DCVs) in neurotransmission?

Contain and release neuropeptides (C) Signup and view all the answers

What is the significance of transporters in sorting neurotransmitters into vesicles?

Critical for sorting classical transmitters into synaptic vesicles (B) Signup and view all the answers

What do neuropeptides not use for fast synaptic transmission?

G-protein-gated receptors (B) Signup and view all the answers

Where are neuropeptides concentrated in cells?

Dense Core Vesicles (DCVs) (A) Signup and view all the answers

What is the difference in the process of synthesis between classical transmitters and neuropeptides?

Neuropeptides can be made locally at the synapse (A) Signup and view all the answers

What is the core difference between neuropeptides and classical transmitters in terms of their transmission?

Neuropeptides use g-gated receptors (D) Signup and view all the answers

Where are peptide transmitters processed before being packaged into regulated secretory vesicles?

Endoplasmic reticulum (ER) and Golgi (C) Signup and view all the answers

What type of neurotransmission is mediated by dopamine and neuropeptides?

Slow neurotransmission (C) Signup and view all the answers

How is fast neurotransmission initiated?

By ligand-gated ion channels (B) Signup and view all the answers

Where are synaptic vesicles transported from before being reused?

Trans-Golgi network (TGN) (C) Signup and view all the answers

Which type of vesicles are released only after specific stimuli and cannot be recycled once peptides are released?

Regulated secretory vesicles (C) Signup and view all the answers

How are proteins sorted into regulated secretory vesicles?

Aggregation at the TGN, facilitated aggregation, sorting by retention, and association with lipid rafts (A) Signup and view all the answers

What are chromogranins and where do they aggregate?

Acidic proteins that aggregate in the TGN (A) Signup and view all the answers

How are neuropeptides cleaved from precursor proteins?

Always cleaved off a precursor protein with di-basic cleavage sites on either side (C) Signup and view all the answers

What processing does amidation refer to in neuropeptides?

Peptidyl-glycine-alpha-amidation in the vesicle (C) Signup and view all the answers

Where do different processing enzymes cleave neuropeptides?

In distinct compartments (C) Signup and view all the answers

What does the egg-laying hormone illustrate?

The importance of timing in the cleavage of neuropeptides (D) Signup and view all the answers

Study Notes

Synthesis and Processing of Peptide Transmitters

Peptide transmitters are synthesized through translation and processed in the endoplasmic reticulum (ER) and Golgi before being packaged into regulated secretory vesicles at the trans-Golgi network (TGN).
Dopamine (DOPINE) and neuropeptides mediate slow neurotransmission, while classical transmitters like glutamate receptors can mediate both fast and slow neurotransmission.
Fast neurotransmission is initiated by ligand-gated ion channels, while slow neurotransmission is initiated by G-protein linked receptors, altering second messengers.
Synaptic vesicles are not newly formed from the TGN but are transported with other axonal proteins in axonal transport vesicles and are reused multiple times.
Regulated secretory vesicles, dense core vesicles, and secretory granules are specialized vesicles in endocrine cells and neurons, released only after specific stimuli and cannot be recycled once peptides are released.
Proteins are sorted into regulated secretory vesicles through aggregation at the TGN, facilitated aggregation, sorting by retention, and association with lipid rafts.
Chromogranins are acidic proteins that aggregate in the TGN, and their removal affects the formation of dense core vesicles.
Neuropeptides are always cleaved off a precursor protein, and they have di-basic cleavage sites on either side.
Neuropeptides have a signal sequence for insertion into the ER through secretory vesicles and may have a glycine signal for amidation.
Neuropeptides undergo processing including signal sequence cleavage in the ER, endoproteolytic cleavage in the TGN or secretory vesicle, and peptidyl-glycine-alpha-amidation in the vesicle.
Different processing enzymes cleave neuropeptides in distinct compartments, and the timing of cleavage is important for sorting them.
The egg-laying hormone is an example that illustrates the importance of timing in the cleavage of neuropeptides.

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Test your knowledge of the synthesis and processing of peptide transmitters with this quiz. Explore topics such as the formation of synaptic vesicles, the role of neuropeptides in neurotransmission, and the mechanisms of peptide sorting and cleavage. Perfect for students and professionals in neuroscience, biochemistry, and pharmacology.