Week 1 (topic 1) Flashcards
What is the relationship between an agonist and a receptor?
- An agonist binds to a receptor, which causes a conformational structural change in the receptor
- Changes include: localisation and nuclear changes in activity
- 1 agonist might act many different types of receptors
- E.g. Acetylcholine (ACh) acts at both muscarinic (GPCRs, mAChR) and nicotinic ACh (ion channels, nAChR) receptors
→ note: nicotinic ACh- also activated by nicotine
What is the Tyrosine kinase?
- stick like structures that sticks out of the cell
- possess kinase activity
- ligands bind and phosphorylate these tyrosine kinase, which produces a pharmacological effect
What is the ligand gated channel?
The ligand (chemical/against) will bind to the receptor → causing the channel to open → allowing ions to move in and out of the cell (changing the polarity of the cell)
What is the GPCR?
- Stands for G protein Coupled receptor
- Consists of a 7 transmembrane spanning
main group
→ giant protein structure that spans the membrane 7 times, hence the name seven transmembrane spanning
What is the GPCR?
- Stands for G protein Coupled receptor
- Consists of a 7 transmembrane spanning
main group
→ giant protein structure that spans the membrane 7 times, hence the name seven transmembrane spanning
What are the 3 subunits that are accompanied after the GPCR?
Heterotrimeric G protein complex (consists of alpha, beta and gamma subunits joined together)
- When an agonist binds to the receptor, the heterotrimeric will bind to the receptor, which splits the alpha, beta and gamma subunits apart
→ Alpha units break apart, become activated and produce adenylate cyclase (a membrane bound enzyme that catalyses the conversion of ATP into cyclic AMP).
What is the intracellular (hormone) receptor?
A receptor that can be in the nucleus or cytoplasm
What is the intracellular (hormone) receptor?
A receptor that can be in the nucleus or cytoplasm
What are the 2 phases of an agonist-receptor interaction?
affinity - agonist binding to the receptor
Efficacy- eliciting an effect; capacity of an agonist to induce the conformational change in the receptor’s structure
What is the agonist binding to receptors governed by?
Governed by the laws of mass action → allows for a simple quantitation of agonist-receptor cell function
The idea that more agonist= greater response to a certain point
Where do agonists come from? Give 3 examples.
Agonists are all over the body. E.g. neurotransmitter, from endocrine
Where do agonists come from? Give 3 examples.
Agonists are all over the body. E.g. neurotransmitter, from endocrine
What is the general form of the relationship between agonist/ antagonist and receptor?
response= [agonist/ antagonist]/[agonist/ antagonist]+ke,
Where:
→ Ke= equilibrium constant, which is a function of the agonist and receptor forming and un-forming a complex together.
- It is essentially a measure of the affinity of an agonist for a receptor
→ Ke= the concentration when the response is at 50%
Describe the features of the agonist binding to the receptor graph
Name of graph: Sigmoidal concentration response curve
Shape of the graph- due to the log concentration units for the x axis —> this shape holds true for any agonist binding at any receptor
→ x- axis= log [agonist] + units (i.e. M or mg/ml)
→ y-axis= response (doesn’t always have to be response, can be anything)
Explain what it means by “the more agonist, the bigger the response…UP TO A POINT.”
Increasing the amount of the agonist will increase the response, however:
→ when all the receptors are already occupied, increasing the amount of agonist will not be able to bind to the receptors (affinity), hence no effect
→ reached maximum capacity of the tissues/ cells
