Drugs and receptors Flashcards
What are targets of drugs?
● Receptors
● Enzymes
● Transporters
● Ion channels
What is a 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
What are the 2 types of ligand?
exogenous (drugs) or endogenous (hormones, neurotransmitter, etc)
Which classes of chemicals communicate using receptors?
- Neurotransmitters → acetylcholine, serotonin
- Autacoids → cytokines, histamine
- Hormones → testosterone, hydrocortisone
What causes allergy?
Increased histamine
What causes Parkinson’s?
Reduced dopamine
What causes Myasthenia gravis?
Loss of Ach receptors
What causes mastocytosis (mast cells)?
Increased c-kit receptor
What are the 4 types of receptor?
- Ligand-gated ion channels
- G protein coupled receptors
- Kinase-linked receptors
- Cytosolic/nuclear receptors
What are ligand-gated ion channels receptors?
nicotinic ACh receptor
What are G protein coupled receptors?
beta-adrenoceptors
What are Kinase-linked receptors for?
receptors for growth factors
What are Cytosolic/nuclear receptors?
steroid receptors
What is the GPCR M3R’s G protein?
Gg
What is the GPCR M3R coupled with?
PLC
What are the 2nd messengers for the GPCR M3R?
IP3/DAG
What is the GPCR β2-AR’s G protein?
Gs
What is the GPCR β2-AR coupled with?
Adenylyl cyclase (AC)
What is the 2nd messenger for the GPCR β2-AR?
Cyclic-AMP
How do kinase-linked receptors work?
- Kinasesare enzyme that catalyse the transfer of phosphate groups between proteins - process is known as phosphorylation
- The substrate gains a phosphate group ”donated” by ATP
- Transmembrane receptors activated when the binding of an extracellular ligand causes enzymatic activity on the intracellular side
- Interaction with ligand on surface causes change of catalytic energy of enzyme → signalling
How do ligand gated ion channels work?
- 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)
- Causes conformational change
How do G protein coupled receptors work?
- act as molecular switches (GDP (guanosine diphosphate) = on, GTP (guanosine triphosphate) = off)
- Targeted by >30% of drugs
- Ligands include light energy, peptides, lipids, sugars and proteins
How do nuclear receptors work?
Work by modifying gene transcription
What is tamoxifen?
- acts as aselective oestrogen receptor modulator(SERM), or as apartial agonistof theoestrogen receptors
- Used in ER+ (oestrogen receptor positive) cancers
