Receptor Families Flashcards
What is a receptor
What does it do
- A receptor is a bifunctional molecule (principal drug target)
- It recognises ligands which reversibly bind to a site and the combination of ligand with receptor triggers a response
What are the 4 receptor superfamilies
- Ion channels
- G-protein-coupled receptors (metabotropic receptors)
- Kinase-linked receptors
- Steroid receptors (IC receptors)
What are GPCRs also known as
Metabotropic receptors
What are steroid receptors also known as
IC receptors
What do VG Ca2+ channels in the heart and BVs influence
Heart rhythm and constriction of BVs
In terms of drugs, what are VG Ca2+ channels a target for (2 points)
- Anti-dysrhythmics (verapamil)
- Anti-hypertensives (amlodipine)
What blocks VG Na+ channels
Local anaesthetics
What is another name for ligand-gated ion channels
Ionotropic receptors
What is a ligand
What happens when a ligand binds to its site on the receptor
Give an example
- A ligand is a small molecule that binds to a receptor
- It causes conformational change, opening the channel and allowing ions to flow through
- Nicotinic receptors to which the endogenous ligand ACh binds
How are ligand gated ion channels activated
By binding of chemical ligand to a site on the channel molecule
Give an example of a ligand-gated ion channel
Explain how it works
Nicotinic ACh receptor
- Nicotine binds and activates the receptor
- Allows Na+ and Ca2+ into the cell
- Stimulant in CNS causes enhanced NT release
- Also causes release of adrenaline from adrenal gland - fight or flight response
What is nicotine in terms of the ACh receptor
A drug that is an exogenous ligand for the ACh receptor
(ACh is the naturally occuring endogenous ligand for this receptor)
Where does the endogenous ligand ACh bind to the nicotinic receptors
What happens as a result
- ACh binds to a site on the alpha subunits opening the channel and allowing Na+ ions to pass through the membrane
Define diazepam
MOA of diazepam
- a benzodiazepine receptor agonist
What is the most abundant class of receptors
What are they also known as
G-protein-coupled receptors
Metabotropic receptors
What is the structure of GPCRs/metabotropic receptors
7 transmembrane helices (heptahelical), with EC domain usually containing the ligand-binding region