Receptors

Question 1

What are the 4 types of receptors?

Answer 1

1) Ligand-gated ion channels
2) G-protein coupled receptors
3) Kinase-linked receptors
4) Nuclear receptors

Question 2

How many transmembrane domains does a G-protein coupled receptor have?

Answer 2

7

Question 3

How many transmembrane domains does a kinase-linked receptor have?

Answer 3

Just one

Question 4

How many transmembrane domains does a nuclear receptor have?

Answer 4

None. Found in nucleus and cytosol

Question 5

What do nuclear receptors control?

Answer 5

The transcription of genes for lipid-based hormones

Question 6

What are the three classes of ligand-gated ion channels?

Answer 6

• Nicotinic acetylcholine receptor
• Glutamate receptor
• P2X receptor

Question 7

Number of transmembrane domains and how many subunits to form a channel: Nicotinic acetylcholine receptor

Answer 7

• 4 transmembrane domains

- 5 subunits required

Question 8

Number of transmembrane domains and how many subunits to form a channel: Glutamate receptor

Answer 8

• 3 transmembrane domains

- 4 subunits required

Question 9

Number of transmembrane domains and how many subunits to form a channel: P2X receptor

Answer 9

• 2 transmembrane domains

- 3 subunits required

Question 10

Which class of ion channels has 3 transmembrane domains and requires 4 subunits to form a channel?

Answer 10

Glutamate receptor

Question 11

Which kind of cholinergic receptors are found at neuromuscular junctions?

Answer 11

Nicotinic

Question 12

Agonist and antagonist of nicotinic acetylcholine receptor?

Answer 12

Agonist: Nicotine
Antagonist: Tubocurarine

Question 13

Agonist and antagonist of GABA receptors?

Answer 13

Agonist: GABA, Phenobarbitone
Antagonist: Picrotoxin

Question 14

What does botulinum toxin do and what is its more common name?

Answer 14

Stops release of ACh

Botox

Question 15

What if the function of G-proteins?

Answer 15

Bind guanine nucleotides

Question 16

What are three subunits of G-proteins?

Answer 16

α alpha
ß beta
γ gamma

Question 17

Activation of G-protein coupled receptor

Answer 17

1. Ligand binds to receptor - activates G-protein
2. GDP unbinds, GTP binds to the activated G-protein at the α-subunit
3. Activated G-protein dissociates into α and ßγ subunits
   The α has a built in timer and has a built in GTPase
4. GTP–>GDP at α-subunit
5. Subunits join back together as GDP-associated α-subunit has strong affinity for ßγ

Question 18

Which part of the G-protein is GDP/GTP bound to?

Answer 18

α-subunit