Receptors Flashcards
What are the 4 types of receptors?
1) Ligand-gated ion channels
2) G-protein coupled receptors
3) Kinase-linked receptors
4) Nuclear receptors
How many transmembrane domains does a G-protein coupled receptor have?
7
How many transmembrane domains does a kinase-linked receptor have?
Just one
How many transmembrane domains does a nuclear receptor have?
None. Found in nucleus and cytosol
What do nuclear receptors control?
The transcription of genes for lipid-based hormones
What are the three classes of ligand-gated ion channels?
- Nicotinic acetylcholine receptor
- Glutamate receptor
- P2X receptor
Number of transmembrane domains and how many subunits to form a channel: Nicotinic acetylcholine receptor
- 4 transmembrane domains
- 5 subunits required
Number of transmembrane domains and how many subunits to form a channel: Glutamate receptor
- 3 transmembrane domains
- 4 subunits required
Number of transmembrane domains and how many subunits to form a channel: P2X receptor
- 2 transmembrane domains
- 3 subunits required
Which class of ion channels has 3 transmembrane domains and requires 4 subunits to form a channel?
Glutamate receptor
Which kind of cholinergic receptors are found at neuromuscular junctions?
Nicotinic
Agonist and antagonist of nicotinic acetylcholine receptor?
Agonist: Nicotine
Antagonist: Tubocurarine
Agonist and antagonist of GABA receptors?
Agonist: GABA, Phenobarbitone
Antagonist: Picrotoxin
What does botulinum toxin do and what is its more common name?
Stops release of ACh
Botox
What if the function of G-proteins?
Bind guanine nucleotides
What are three subunits of G-proteins?
α alpha
ß beta
γ gamma
Activation of G-protein coupled receptor
- Ligand binds to receptor - activates G-protein
- GDP unbinds, GTP binds to the activated G-protein at the α-subunit
- Activated G-protein dissociates into α and ßγ subunits
The α has a built in timer and has a built in GTPase - GTP–>GDP at α-subunit
- Subunits join back together as GDP-associated α-subunit has strong affinity for ßγ
Which part of the G-protein is GDP/GTP bound to?
α-subunit
