Lect 4 - Different receptor types

Question 1

what are the 4 receptor types

Answer 1

1. ion channels
2. g-protein coupled receptors
3. tyrosine kinase phosphorylase receptor
4. nucleate receptor

Question 2

explain how type 1 receptor works, and give an example

Answer 2

ligand gated ion channels (ACh) - these receptors work by opening the ion channel when ACh binds to it, this leads to depolarisation of the cells which can start a chain of events. drugs that target these receptors work by either blocking channels from opening, or by keeping the channel open and not allowing repolarisation or another signal to be sent out.
e.g. succinylcholine

Question 3

explain how type 2 receptor works, and give an example

Answer 3

g-protein coupled receptors -

Question 4

explain how type 3 receptor works, and give an example

Answer 4

tyrosine-kinase receptors - e.g. human growth hormone, bind to receptor, undergoes conformational change and dimerisation, this leads to tyrosine kinase domain expressing free phosphates which reacts with intracellular protein to start signal cascade. drug against this work by either blocking dimerization, or blocking binding. e.g. trastuzumab.

Question 5

explain how type 4 receptor works, and give an example

Answer 5

nuclear receptor - these bind to drugs which can move across the cellular and the nuclear membrane. the structure of these drugs are analogous to the natural substrate. it gets transported into the nucleus. it must be dimerised in order to interfere with DNA transcription to produce an effect. e.g. Prednisolone.

as a consequence of regulating gene expression, these drugs are slow acting, and action persists long after the drug has cleared the system.