Structure Of Receptors Flashcards
Define receptor
A molecule that specifically recognises a second molecule (ligand) or family of molecules and which is in response to ligand binding, brings about a cellular response.
What is the difference between receptors and acceptors?
Receptors are functionally silent when unbound. Acceptors still contributes to the cellular process when unbound and only modulate their behaviour when bound.
What is Kd?
The concentration of ligand that fills half the receptor sites
How many types of muscarinic receptor are there?
5
M1-M5
Name 3 receptors with an integral ion channel
nAChR
GABA receptors
IP3 receptors
Describe the structure of nAChR
Pentameric (5 subunits)
Channel in the centre of the subunits
2 alpha subunits that bind ACh to open
In ‘classical’ ligand gated ion channels, where is the N terminus?
On the outside of the cell
Name 2 non-classical LG ion channels
ATP sensitive K+ channel
Ryanodine receptors
Name 4 receptors with integral enzyme activity
ANP receptor (cardiac)
Insulin receptor
EGF receptor
PDGF receptor
Which receptors are linked directly to tyrosine kinase?
Insulin receptor
EGF receptor
PDGF receptor
What are SH2 domains?
Phospho recognition sites
What is another name for GPCRs?
7 TMD receptors
What is the brief, general pathway when adrenaline binds to beta adrenoceptors?
G alpha s activated
Activates adenylyl cyclase to produce more cAMP
What is the brief, general pathway when ACh binds to M2 receptors?
G alpha i subunit activated
Stimulates K+ channel opening
How are the DNA binding domains of intracellular receptors sometimes described?
Zinc fingers
What stops the intracellular receptor binding to DNA at rest?
The DNA binding domain is blocked by an inhibitory protein
Noradrenaline acts on which receptors in the heart to increase HR?
Beta 1 adrenoceptors
ACh acts on which receptors in the heart to decrease HR?
M2 muscarinic receptors
What are the 3 basic types of signalling molecules?
Local mediators
Hormones
Neurotransmitters
Define affinity
The measure of the ability of a drug (ligand) to form a drug-receptor complex
Define efficacy
The measure of the ability of the drug-receptor complex to produce a response
If the dose response curved is higher, it has a greater …
Efficacy
If the dose response curve is to the left it has a greater…
Potency
Define tachyphylaxis
Excessive exposure to agonist causes reduced sensitivity due to receptor down-regulation
Define suprasensitivity
Upregulation of receptors due to agonist deprivation or excessive antagonist exposure
What are the effects of opioids?
Analgesia
Sedation
Euphoria
Where are SERMs agonists?
Bone and uterus
Why aren’t receptors down regulated in patients with a pheochromocytoma?
The secretions of adrenaline and NA are intermittent
Symptoms actually worsen over time
