Intracellular Signalling Pathways Flashcards
What are the 3 super families of cell-surface receptors? Give an example of each
- G-Protein Receptors (muscarinic acetylcholine receptors)
- Ligand-Gated Ion Channels (nicotinic acetylcholine receptors)
- Intrinsic Enzymatic Activity Receptors (tyrosine kinase)
What do agonist have that antagonists don’t?
Efficacy
Name 2 pharmaceutical agonists and their receptors
Beta 2 adrenoceptor - Salbutamol
Mew opioid receptor- Morphine
Name 2 pharmaceutical antagonists and their receptors
Beta 1 receptor- Propanalol
D2 dopamine receptor - Haloperidol
Name 2 things GPCRs can respond to
- Ions
- Neurotransmitters
- Peptide and non-peptide hormones
- Large glycoproteins
What are the four basic elements of a GPCR?
- Single polypeptide chain
- 7 transmembrane spanning regions
- Extracellular N-terminal
- Intracellular C-terminal
In which two places can a ligand bind?
- Between transmembrane proteins
- N-terminal/Extracellular domains
What is the first process after a ligand has bound to a GPCR?
- G-Protein is attracted to activates GPCR
- G-Protein activates and GDP on alpha subunit is converted to GTP
What terminates the action of a GPCR reaction and how?
- GTPase hydrolyses GTP back to GDP
- 3 subunits recombine
- Effector ceases
Give 2 reaction pathways of GPCRs in terms of ligand, GPCR, Effector and Reaction
Adrenaline > Beta-Adrenoceptor > Adenylyl Cyclase stimulates conversion of ANP to cAMP
Acetylcholine > M2/M4 muscarinic receptor > Adenylyl Cyclase is inhibited
What effect does the cholera toxin have on the GPCR process?
- It stops the action of GTPase
- Effector continues to work
- Water and electrolytes leave intestine
What is the overall effect of toxins on GPCR process?
The toxin complex binds to the cell and an enzyme is injected into the cell
What effect does Pertussis toxin have on the GPCR process?
Stops exchange of GDP to GTP
- ‘Uncouples’ GPCRs from meditating signal transduction events
- Causes whooping cough
