21. Antagonists Flashcards
What is an antagonist?
A ligand that binds to a receptor
Produces no biological response
prevents other ligands from binding
What is a competitive antagonist?
Binds to the same site as the agonist
Reversible binding
Increased amount of agonist is require
Maximum effect is unchanged
What is a non-competitive antagonist?
Binds to a different site than the antagonist
Can’t be overcome by increasing the agonist concentration
Decreased maximum effect
What is a reversible antagonist?
Can be displaced by other ligands
Binds non-covalently
What is an irreversible antagonist?
Covalent binding to a receptor
What is an inverse agonist?
Produces the opposite response to the agonist
Why might desensitisation occur?
- Change/loss of receptors
- Reduction of signalling proteins within the cell
- Increased metabolic degradation
- Physiological adaptation
What is a permissive antagonist?
Allows some parts of the signalling cascade to occur but not all
GPIIb/IIIa
