Sossin 2: neuropeptides

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Questions and Answers

What is the minimum number of amino acids required for a signal sequence to appear out of the ribosome during co-translational insertion?

50 (correct)

What is the primary reason for the biosynthesis of neuropeptides as precursors?

To increase the rate of peptide production

To provide flexibility in processing and regulation (correct)

To reduce the energy required for peptide synthesis

To utilize the rough endoplasmic reticulum more efficiently

In which part of the cell does the cleavage of neuropeptide precursors occur?

Ribosome

Rough endoplasmic reticulum

Trans-Golgi network or immature/mature secretory vesicles (correct)

Golgi apparatus

What is the evolutionary significance of peptide-based communication?

It predates the nervous system Signup and view all the answers

Why are neuropeptide genes transcribed into mRNA?

To facilitate the translation of proteins Signup and view all the answers

What is the significance of signal sequence cleavage during neuropeptide biosynthesis?

It removes the signal sequence from the precursor protein Signup and view all the answers

What role do neuropeptides play in regulating specific behaviors?

Regulating mood, eating, and water balance Signup and view all the answers

Which of the following peptides is NOT a neuropeptide?

Insulin Signup and view all the answers

What type of receptors mediate slow synaptic transmission?

G protein-linked receptors Signup and view all the answers

What is a key difference between the regulated release of neuropeptides and endocrine peptides?

The role of calcium is similar in both cases Signup and view all the answers

What is a characteristic feature of peptide transmitters?

They are ancient and predated the evolution of neurons Signup and view all the answers

What is an example of a neuropeptide that regulates feeding behavior?

NPY Signup and view all the answers

What is the primary reason for TM proteins to aggregate and then sort during the secretory pathway?

To increase the efficiency of prohormone processing Signup and view all the answers

Where do Furin and prohormone convertases cleave the peptides from their precursors?

Furin in the TGN and PCs in immature secretory granules Signup and view all the answers

What is the minimum sequence required for Furin recognition?

Basic X Basic Basic Signup and view all the answers

What is the function of peptidyl-glycine-alpha-amidation in the secretory vesicle?

Conversion of glycine into an amine group Signup and view all the answers

At what level is the regulation of neuropeptides predominantly controlled?

Gene expression Signup and view all the answers

What is the primary function of prohormone convertases in the secretory pathway?

Cleavage of the prohormone into mature neuropeptides Signup and view all the answers

What is the primary function of G protein-linked receptors in cellular communication?

To directly regulate the mechanisms of fast neurotransmission Signup and view all the answers

What is the role of the alpha subunit in the G protein complex?

To bind to GTP and become an effector Signup and view all the answers

What is the effect of Gs G proteins on adenylate cyclase?

They increase adenylate cyclase activity Signup and view all the answers

What is the role of RGS proteins in G protein signaling?

To inhibit G protein activation Signup and view all the answers

What is the characteristic of the beta/gamma subunit of G proteins?

They are tightly linked and can act as effectors Signup and view all the answers

What is the primary function of Gq G proteins?

To increase phospholipase C Signup and view all the answers

What is the effect of noradrenaline on beta-adrenergic receptors and alpha-adrenergic receptors?

It activates adenylate cyclase in beta-adrenergic receptors and inhibits it in alpha-adrenergic receptors Signup and view all the answers

What is the difference between D1 and D2 receptors in the striatum?

D1 is Gs coupled and D2 is Gi coupled Signup and view all the answers

During slow EPSPs, what type of channels are most likely affected?

Opening resting Cation channels (Na and K+) Signup and view all the answers

What is the effect of slow IPSPs on the post-synaptic neuron?

It decreases the likelihood of the post-synaptic neuron to fire Signup and view all the answers

What type of receptors are involved in the effect of odorants, taste, and light on the neuron?

G protein linked receptors Signup and view all the answers

What is the effect of ligand-gated ion channels on neurotransmission?

It changes the size of the fast EPSPs and IPSPs Signup and view all the answers

Study Notes

Neuropeptides and their Roles

Neuropeptides are involved in regulating various physiological processes, such as mood, eating, water balance, and sleep.
Specific neuropeptides are associated with specific functions, e.g., opioids with pain, ghrelin and GLP-1 with feeding, and orexins with sleep.

Difference between Endocrine Peptides and Neuropeptides

Non-neuronal peptides are processed similarly to neuropeptides, e.g., insulin and GLP-1.
Regulated release of peptides differs in endocrine cells, with calcium and cAMP being important.

Peptide Transmitters

Peptide transmitters are ancient and predate the nervous system.
Neuropeptides and other modulatory transmitters use slow synaptic transmission.
G protein-linked receptors mediate slow synaptic transmission, altering cell potential through ion channel regulation.

Biosynthesis of Neuropeptides

Neuropeptides are made as precursors, which cannot be inserted into the ER cotranslationally due to their small size (minimum of 50 aa).
This allows for flexibility, regulation of processing, and mechanism for generating diversity.
Evolutionary history shows that peptide-based communication predates the nervous system.

Slow Neurotransmission

Slow EPSPs and IPSPs occur through the regulation of ion channels, affecting the shape of the action potential.
Ligand-gated ion channels are affected, with different channels being affected by different ligands.
G protein-linked receptors alter the potential of the cell through regulation of ion channels.

G Protein-Linked Receptors

There are more different G protein-linked receptors than any other type of protein.
G protein-linked receptors are used by classical neurotransmitters, neuropeptides, and sensory inputs.
Ligands bind to G protein-linked receptors, affecting downstream effects.

Regulation of Neuropeptides

Regulation of neuropeptides occurs at the level of gene expression, with cells expressing new neuropeptides through increasing gene expression.
Regulation also occurs through direct regulation of the mechanisms of fast neurotransmission, altering the probability of release.
G protein-linked receptors are involved in the regulation of neuropeptides.

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Description

Learn about the characteristics of GABAergic neuron subtypes, including their neuropeptide co-transmitters such as VIP, Somatostatin, CCK, and NPY. Understand why neuropeptides are made as precursors and how they are processed.