Receptors and Membrane Signalling Flashcards
What is Kd?
- Affinity; binding strength.
- The dissociation constant.
What is Emax?
Efficacy; maximum response achievable.
What type of signalling molecules are said to possess both affinity and efficacy?
Agonists.
Define potency.
- A measure of drug activity - a highly potent drug is only required in a very small dose.
- Hence related to affinity.
Define quantitative pharmacology.
Pharmacology based on the assumption that:
- Drugs act by entering into a simple chemical relation with receptors.
- There is a simple relation between the amount of drug fixed and the action produced.
What is the shape of a graph of response / [agonist]?
A hyperbole.
What is the shape of a graph of response / log [agonist]?
A sigmoid.
How can a graph of response / log [agonist] be used to determine Kd?
- Kd = EC50.
- Kd is therefore the value of log [agonist] where response = 50%.
Define super-agonist.
An agonist which can produce a maximal response without binding to all of the available receptors.
Give an example of a super-agonist and describe its function.
- Zoladex.
- A gonadotropin-releasing hormone receptor that suppresses production of sex hormones.
- Useful in the treatment of breast and prostate cancer.
Define partial agonist.
An agonist which cannot produce a maximal response, even when bound to all of the available receptors.
Give an example of a partial agonist and describe its function.
- Buprenorphine.
- An opioid used to treat opioid addiction and moderate pain.
What are ‘dirty drugs’?
A drug that may bind to multiple different receptors.
Give an example of a dirty drug and describe its function.
- Quetiapine.
- An antipsychotic.
From which species of fungus can muscarine be obtained?
Amanita muscaria.
What is atropine?
Where can it be obtained?
- An antagonist to muscarinic receptors.
- From Atropa belladonna.
List 5 receptor super-families.
1 - Integral ion channels.
2 - Integral tyrosine kinases.
3 - Steroid receptors (nuclear receptors).
4 - GPCRs.
5 - Cytokine receptors.
List the regions of the response element of nuclear receptors to which DNA and ligands bind.
- DNA binding domain.
- Ligand binding domain.
List 2 examples of integral ion channels.
1 - Nicotinic receptors.
2 - Glycine receptors.
Give an example of an integral tyrosine kinase receptor.
Insulin receptors.
List 2 examples of steroid (nuclear) receptors.
1 - Oestrogen receptors.
2 - Androgen receptors.
List 2 examples of GPCRs.
1 - Muscarinic receptors.
2 - Adrenoreceptors.
List 3 examples of cytokine receptors.
1 - Prolactin receptors.
2 - Growth hormone receptors.
3 - TNF receptors.
List 4 ways in which drugs can regulate cell function.
1 - By altering membrane potential.
2 - By altering enzyme activity.
3 - By altering gene expression.
4 - Via physiological receptors.
