Drugs And Receptors 16.11.23 Flashcards
(31 cards)
Define receptor?
A component of a cell that interacts with a specific ligand* and initiates a change of biochemical events leading to the ligands observed effects
*Ligands can be exogenous (drugs) or endogenous (hormones, neurotransmitter, etc)
What 3 types of chemicals can communicate through receptors?
Neurotransmitter —> acetylcholine, serotonin
Autacoids (local) —> cytokines, histamine
Hormones —> testosterone, hydrocortisone
What are the 4 types of receptor?
Ligand-gated ion channels —>
nicotinic ACh receptor
G protein coupled receptors —> beta-adrenoceptors
Kinase-linked receptors —>
receptors for growth factors
Cytosolic/nuclear receptors —> steroid receptors
What are ligand gated ion channels?
Ion channelsare pore-formingmembrane proteinsthat allowionsto pass through the channel pore so that the cell undergoes a shift inelectric chargedistribution
The change in charge can be mediated by an influx of any kind ofcation(+ve) or efflux of any kind ofanion (-ve).
What are GCPRs?
GPCRs are the largest and most diverse group of membrane receptors in eukaryotes. (they have 7 membrane spanning regions)
What is a G protein also known as?
Guanine nucleotide-binding proteins
What do G proteins do?
G proteins are involved in transmitting signals from GPCRs
How are G protein activity regulated?
Their activity is regulated by factors that control their ability to bind to and hydrolyzeguanosine triphosphate(GTP) toguanosine diphosphate(GDP)
What are kinases?
Kinasesare enzyme that catalyze the transfer of phosphate groups between proteins - process is known as phosphorylation.
How does kinase-linked receptors work?
The substrate gains a phosphate group ”donated” by ATP
How do nuclear receptors work?
Work by modifying gene transcription, zinc fingers, bind DNA
There are situations where an imbalance of chemicals/receptors can lead to pathology.
Allergy results in increased what levels?
Increased histamine
There are situations where an imbalance of chemicals/receptors can lead to pathology.
Parkinson’s results in decreased what levels?
Decreased dopamine
There are situations where an imbalance of chemicals/receptors can lead to pathology.
Myasthenia gravis results in a loss of what?
Loss of ACh receptors
There are situations where an imbalance of chemicals/receptors can lead to pathology.
Mastocytosis results in increased what levels?
Increased c-kit receptor
Define agonist (in terms of receptors)
A compound that binds to a receptor and activates it
Define antagonist (in terms of receptors)
a compound that reduces the effect of an agonist
Learn the two state model of receptor activation - it describes how drugs activate receptors by inducing or supporting a conformational change in the receptor from “off” to “on”.
Define intrinsic activity
Intrinsic activity(IA) orefficacyrefers to the ability of a drug-receptor complex to produce a maximum functional response
Learn what full agonist, partial agonist and intrinsic activity mean (see lecture)
Define competitive antagonism
Binds to the same site
Define non-competitive antagonism
Binds to an allosteric (non-agonist) site on the receptor to prevent activation of the receptor
What are the 2 categories of cholinergic receptors?
Nicotinic and muscarinic
What are the 4 factors governing drug action?
(Receptor-related —>)
affinity
efficacy
(Tissue-related —>)
receptor number
signal amplification
