Bio Signalling And Receptors-drug Targets Flashcards
What is Pharmacokinetics?
The way the body handles drugs
What are the 5 ways of intracellular signalling?
Signal by secreted molecules (cell secretes signal molecule and t binds to receptor on target cell)
Signal by plasma membrane-bound molecules (signal molecule is bound 2 membrane, binds to receptor on target cell)
Paracrine (signal cell releases local mediator to local cells)
Endocrine (signal cel releases hormone into blood to travel to target cell at another body site)
Synaptic (neurotransmitter released across synaptic cleft to target)
What are cell surfaces receptors and when are they used?
Receptor is on the outside of plasma membrane.
Used when the signalling molecule cant enter the cell. May be because its hydrophilic (as its water soluble it cant pass lipid membrane)
What are intracellular receptors and when are they used?
The receptor is in the cytoplasm or nucleus.
Used when the signal molecule needs to work on DNA or in the cell.
The signal molecule is carried on a protien in the blood it doesn’t transport alone. It’s small and hydrophobic so can pass the lipid membrane into the cell.
What is a receptor?
A receptor is a molecule that recognises specifically a second molecule (ligand) or family of molecules and which in response to ligand bonding brings about regulation of a cellular process.
(In the unbound state its silent)
What is a ligand? When is it an agonist or antagonist?
Ligand is any molecule that bind specifically to a receptor site.
Agonist=binding produces activation of a receptor.
Antagonist=ligand binds and doesn’t cause activation, does block/oppose the action of an agonist.
What is the role of receptors in cellular physiology?
Signal by hormones/local chemical mediators Neurotransmission Cellular delivery (nutrients etc) Control of gene expression Cell adhesion Modulation of immune response Storing intracellular protein Release of intracellular calcium sites (maintain safe levels)
Describe binding affinity at receptor sites.
Affinity of ligand binding at receptor sites is generally much higher than being on substrates and allosteric regulators to enzyme sites
Kd is the conc at which ligand half fill receptor sites
How are Receptors classified?
They are classified according to which specific signalling molecule they recognise (eg acetylcholine receptors)
They are then sub-classified by affinity of a series of antagonist
How do we decide which antagonist is used to sub-classify a receptor?
Many receptors have the same series of antagonists but each antagonist will bind to each receptor with a different affinity. So the antagonist that is most effective on a receptor will give it its subdivision.
What’s the difference between a receptor and acceptor?
Receptor=salient at rest, agonist binding stimulates biological response
Acceptor=operate in absence of ligand (have Basal activity), a ligand binging alone doesn’t produce a response EG a sodium channel works on voltage but can accept the binding of neurotoxins so is an acceptor
How are signals transducer across the membrane (signals from outside reaching inside)?
Membrane-bound receptors with integral ion channels
Membrane-bound receptors with integral enzyme activity
Membrane-bound receptors which couple to effectors via transduction get proteins
Intracellular receptors
What is the structure of a nicotinic acetylcholine receptor? This is the classical receptor family..
Pentameric -5 units
2 units have binding sites
Creates a pore
What are some ligand-gated ion channels classed as non classical?
They are not pentameric ligand gated
How do membranes bound receptors with integral activity function? And what is structure?
Have 2 binding domains, then a rigid alpha helix through the membrane , then 2 catalytic domains.
The a-helix is rigid so cannot get a conformational change across the membrane. So the binding and catalytic domain act as diamers to get info across.
