ELM 5.1

Question 1

What is transduction?

Answer 1

Passes on signal / information in a different form

Question 2

what is the largest class of receptors?

Answer 2

G-protein related receptors

Question 3

How do G-protein coupled receptors work?

Answer 3

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

Question 4

Receptor tyrosine kinase

Answer 4

triggers protein kinase activity inside - recognizes target proteins due to specific signalling sequence

Question 5

Nuclear hormone receptor

Answer 5

intercellular - when bind to agonist, receptor interacts with specific segments of DNA - change cell behaviour by changing production rate of particular proteins

Question 6

Allosteric modulator

Answer 6

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)

Question 7

What are the two groups of ligand gated ion channels?

Answer 7

Cys loop receptors and ionotropic glutamate receptors

Question 8

Characteristics of ligand-gated ion channels (4)

Answer 8

• 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

Question 9

How many transmembrane domains in the g protein coupled receptors?

Answer 9

7

Question 10

What do all g-protein coupled receptors have (inner and outer sides)

Answer 10

G-protein binding domain on inner face (intercellular side) and an extracellular binding site

Question 11

What is another name for g-protein coupled receptors?

Answer 11

Metabotropic receptors (maybe serpentine receptors)

Question 12

What are the three main types of g protein?

Answer 12

Gs, Gi, Gq

Question 13

What alpha subunit does Gs contain? (And what does it bind to/what effect does it have)

Answer 13

alpha s - adenylate cyclase: increases cAMP

Question 14

What alpha subunit does Gi contain? (And what does it bind to/what effect does it have)

Answer 14

alpha i - adenylate cyclase: decreases cAMP

Question 15

What alpha subunit does Gq contain? (And what does it bind to/what effect does it have)

Answer 15

alpha q - phospholipase C: increase IP3 - diacylgycerol - increased cytoplasmic Ca2+

Question 16

what do astrocytes do?

Answer 16

metabolizes glutamate to glutamine - this can be taken back up (glutamine is inert)

Question 17

What are the three classes of ionotropic receptors?

Answer 17

AMPA (quisqualate)
Kainate
NMDA
(all bind glutamate as their natural ligand)

Question 18

What two types of glutamate receptors?

Answer 18

Ionotropic and Metabotropic

Question 19

Metabotropic receptors always operate as ___

Answer 19

dimers

Question 20

In family A receptors, the agonist binding site is located where?

Answer 20

along the tops of the transmembrane domains

Question 21

Which produce faster responses? Ionotropic or metabotropic receptors?

Answer 21

Ionotropic

Question 22

We need two ___ and two ___ to bind to four subunits for it to be activated

Answer 22

glutamate and glycine

Question 23

what are inhibitory glycine receptors closely related to?

Answer 23

GABAA receptors

Question 24

As cAMP increases the activity of voltage gated calcium channels, and thus noradrenaline release, the consequence of activating the alpha 2 autoreceptors is what ?

Answer 24

To decrease noradrenaline release

Question 25

The antidepressant mirtazapine is an antagonist of what

Answer 25

alpha 2 receptors

Question 26

What does blocking alpha 2 receptors do?

Answer 26

results in an increase in noradrenaline release (and serotonin release)

Question 27

What is the difference between a heteroreceptor and an autoreceptor?

Answer 27

Whereas an autoreceptor responds to the neurotransmitter released by the neurone whose membrane it is embedded in, a heteroreceptor responds to a different neurotransmitter.

Question 28

what is a key problem in parkinson’s disease?

Answer 28

a deficit in dopaminergic transmission in the striatum

Question 29

an excess of dopamine in a different part of the striatum is thought to be involved in some of the symptoms of ?

Answer 29

schizophrenia

Question 30

if you see alpha at the front of a toxin name, what does that usually mean?

Answer 30

it targets nicotinic acetylcholine receptors

Question 31

lynx 1 describe

Answer 31

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).

Question 32

Which of the following are metabotropic receptors (GPCRs)?

Answer 32

Dopamine receptor
GABAB receptor
muscarinic acetylcholine receptor

Question 33

Drug X binds to NMDA receptors and induces an influx of calcium into cells. Drug X could be a(n):

Answer 33

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.

Question 34

a ligand that does NOT bind to nicotinic acetylcholine receptors.

Answer 34

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.

Question 35

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?

Answer 35

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).

Question 36

An example of a neurotransmitter acting on a heteroreceptor is:

Answer 36

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.