Molecular Targets of Drug Action

Question 1

What is a receptor?

Answer 1

A biological macromolecule or complex that binds another molecule and initiates or modulates signalling or effecter activity within a cell

Question 2

What is a ligand?

Answer 2

A molecule that binds to a receptor

Question 3

What is an agonist?

Answer 3

A ligand that binds to a receptor and activates it

Question 4

What is an antagonist?

Answer 4

A ligand that binds to a receptor without activating it

Question 5

What are the features of the beta-adrenoceptor?

Answer 5

GPCR, responsive to adrenaline and noradrenaline, stimulatory in some tissues (heart), inhibitory in others (bronchial), agonist: isoprenaline, antagonist: propranolol

Question 6

What are the four categories of receptors?

Answer 6

Ligand gated ion channel receptors, GPCRs, kinase linked receptors, nuclear receptors

Question 7

What are the features of ligand gated ion channel receptors?

Answer 7

Binding results in hyper polarisation or depolarisation, acts very quickly e.g. nicotinic receptors

Question 8

What are the features of GPCRs?

Answer 8

7 transmembrane regions, linked to effector by G protein, takes a little longer to act than ion channel receptors

Question 9

What are the features of kinase-linked receptors?

Answer 9

Usually tyrosine or serine kinases, phosphorylates proteins, takes longer to act than GPCRs

Question 10

What are the features of nuclear receptors?

Answer 10

Intracellular receptors, binding causes a change in gene transcription, ligands are lipid soluble