2 - Intracellular signalling Flashcards
What is signal transduction?
After initial ligand binding, chain of molecules relay intracellular signals to generate a response
What are the big 3 cell surface receptors?
G protein coupled receptors
Ligand gated ion channels
Receptors with intrinsic enzymatic activity
Name an example of a GPCR
Muscarinic acetylcholine receptors
Name an example of a ligand gated ion channel
Nicotinic acetylcholine receptors
Name an example of a receptor with intrinsic enzymatic activity
Receptor tyrosine kinases - insulin receptors
Define an agonist
Binds to receptor and activates it, leading to transduction of signal
Define an antagonist
Binds to receptor but does not activate it, blocking the effects of an agonist
How are agonists used to treat asthma?
B2 adrenoreceptor agonists eg Salbutamol, bronchodilator of smooth muscle
How are antagonists used to treat hypertension?
B adrenoreceptor antagonists eg Propanolol and atenolol, slows heart rate and reduces force of contraction
Propanolol also causes bronchoconstriction
Where can ligands bind to a GPCR?
Transmembrane domains
Extracellular N-terminal
How is a specific cellular response generated from GPCR activation?
High diversity in each type of subunit
Activated GPCR’s preferentially interact with specific G proteins, with alpha sub-unit being determinant
The different subunits interact with specific effector proteins
What are the 3 types of alpha subunit?
S, I and Q
What is the function of the Alpha subunit S?
Stimulate adenylyl cyclase
Which hydrolyses ATP to form cAMP
cAMP interacts with PKA
What is the function of the alpha subunit I?
Inhibits adenylyl cyclase
What is the function of alpha subunit Q?
Stimulate phospholipase C
Which hydrolyses PIP2
Generates DAG and IP3
