ELM 5.1 Flashcards
What is transduction?
Passes on signal / information in a different form
what is the largest class of receptors?
G-protein related receptors
How do G-protein coupled receptors work?
Recognize signal outside cell, interacts with accessory protein (the g protein - trimeric) - when they interact, the GDP is replace with GTP. these signals trigger intercellular cascades
Receptor tyrosine kinase
triggers protein kinase activity inside - recognizes target proteins due to specific signalling sequence
Nuclear hormone receptor
intercellular - when bind to agonist, receptor interacts with specific segments of DNA - change cell behaviour by changing production rate of particular proteins
Allosteric modulator
An allosteric modulator binds to a site distinct from the agonist site and changes receptor behaviour. Allosteric modulators can either be positive (increase receptor activity) or negative (decrease receptor activity)
What are the two groups of ligand gated ion channels?
Cys loop receptors and ionotropic glutamate receptors
Characteristics of ligand-gated ion channels (4)
- pore - lets ions through
- ligand binding site - tells channel to open in response to ligand binding
- coupling mechanism - couples channel opening to ligand binding
- desensitization mechanisms - close channel if ligand binds for too long
How many transmembrane domains in the g protein coupled receptors?
7
What do all g-protein coupled receptors have (inner and outer sides)
G-protein binding domain on inner face (intercellular side) and an extracellular binding site
What is another name for g-protein coupled receptors?
Metabotropic receptors (maybe serpentine receptors)
What are the three main types of g protein?
Gs, Gi, Gq
What alpha subunit does Gs contain? (And what does it bind to/what effect does it have)
alpha s - adenylate cyclase: increases cAMP
What alpha subunit does Gi contain? (And what does it bind to/what effect does it have)
alpha i - adenylate cyclase: decreases cAMP
What alpha subunit does Gq contain? (And what does it bind to/what effect does it have)
alpha q - phospholipase C: increase IP3 - diacylgycerol - increased cytoplasmic Ca2+
what do astrocytes do?
metabolizes glutamate to glutamine - this can be taken back up (glutamine is inert)
What are the three classes of ionotropic receptors?
AMPA (quisqualate)
Kainate
NMDA
(all bind glutamate as their natural ligand)
What two types of glutamate receptors?
Ionotropic and Metabotropic
Metabotropic receptors always operate as ___
dimers
In family A receptors, the agonist binding site is located where?
along the tops of the transmembrane domains
Which produce faster responses? Ionotropic or metabotropic receptors?
Ionotropic
We need two ___ and two ___ to bind to four subunits for it to be activated
glutamate and glycine
what are inhibitory glycine receptors closely related to?
GABAA receptors
As cAMP increases the activity of voltage gated calcium channels, and thus noradrenaline release, the consequence of activating the alpha 2 autoreceptors is what ?
To decrease noradrenaline release
The antidepressant mirtazapine is an antagonist of what
alpha 2 receptors
What does blocking alpha 2 receptors do?
results in an increase in noradrenaline release (and serotonin release)
What is the difference between a heteroreceptor and an autoreceptor?
Whereas an autoreceptor responds to the neurotransmitter released by the neurone whose membrane it is embedded in, a heteroreceptor responds to a different neurotransmitter.
what is a key problem in parkinson’s disease?
a deficit in dopaminergic transmission in the striatum
an excess of dopamine in a different part of the striatum is thought to be involved in some of the symptoms of ?
schizophrenia
if you see alpha at the front of a toxin name, what does that usually mean?
it targets nicotinic acetylcholine receptors
lynx 1 describe
Lynx 1 is a soluble protein regulator of neuronal nicotinic receptors. It is very important in brain development. In hollow fanged (elapid) snakes, proteins related to Lynx 1 have evolved to become toxins. They target muscle nicotinic acetylcholine receptors. Examples include α-cobra toxin and α-bungarotoxin (from the cobra and Taiwanese banded krait respectively).
Which of the following are metabotropic receptors (GPCRs)?
Dopamine receptor
GABAB receptor
muscarinic acetylcholine receptor
Drug X binds to NMDA receptors and induces an influx of calcium into cells. Drug X could be a(n):
agonist or partial agonist:
An agonist is a drug that activates a receptor. A partial agonist is one that activates, but is not able to produce the same maximal effect as a “full” agonist. Thus, drug X could be either an agonist or a partial agonist.
a ligand that does NOT bind to nicotinic acetylcholine receptors.
Omega conotoxin:
Toxins with an ‘alpha’ at the front of their name are most likely to be ligands at nicotinic acetylcholine receptors (alpha conotoxin, alpha bungarotoxin and alpha cobra toxin). Lynx is a neuromodulatory peptide that acts on nicotinic acetylcholine receptors in the brain. Omega conotoxin, however, inhibits calcium channels.
The hobbit uses the amino acid alanine as a neurotransmitter in its spinal cord. At one common type of synapse, alanine is released by the presynaptic nerve terminal and binds to alanine type A receptors on the post-synaptic neurone. Alanine also binds to alanine type B receptors on the presynaptic nerve terminal. Activation of these type B receptors causes negative feedback on alanine release.
What is the most appropriate description for the alanine type B receptors?
autoreceptor
A receptor that binds the neurotransmitter released by the neurone in whose membrane it is embedded, is known as an autoreceptor (a less common name is a homoreceptor).
An example of a neurotransmitter acting on a heteroreceptor is:
acetylcholine acting on presynaptic nicotinic receptors at a dopaminergic nerve terminal:
A heteroreceptor is a receptor that binds a neurotransmitter other than the transmitter released by the neurone in whose membrane the heteroreceptor sits.
