drug & receptors Flashcards
give 4 targets of drugs
receptors
enzymes
transporters
ion channels
define drug
a medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body
define pharmacology
the branch of medicine concerned with the uses, effects and modes of action of drugs
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.
what are the 2 categories of ligand
exogenous - drugs
endogenous - hormones, neurotransmitters etc
how do chemicals communicate
via receptors
give examples of chemicals
neurotransmitters - acetylcholine, serotonin
autacoids (local) - cytokines, histamine
hormones - testosterone, hydrocortisone
give 4 types of receptors
- ligand gated ion channels
- g protein coupled receptors
- kinase-linked receptors
- cytosolic/nuclear receptor
example of ligand gated ion channel
nictonic ACh receptor
describe g protein coupled receptors
they are the largest and most diverse group of membrane receptors in eukaryotes
G proteins act as molecular switches (GDO = on. GTP= off)
Targeted by >30% of drugs
Ligands include light energy, peptides, lipids, sugars and proteins
what are ion channels
pore forming membrane proteins that allow ions to pass through the channel pore so that the cell undergoes a shift in electric charge distribution
what can mediate a change in charge
an influx of any kind of cation (+ve) or an influx of any kind of anion (-ve)
what are g proteins also known as
guanine nucleotide binding proteins
a family of proteins (35) involved in transmitting signals from GPCRs
what regulates activity of g proteins
factors that control their ability to bind and hydrolyse gunaosine triphosphate to guanisine diphosphate
what chemical causes allergies
increased histamine
what chemical causes parkinsons
reduced dopamine
what are kinases
enzymes that catalyse the transfer of phosphate groups between proteins - phosphorylation
the substrate gains a phosphate group donated by ‘ATP’
how do kinase linked receptors work
transmembrane receptors become activated when the binding of an extra cellular ligand causes enzymatic activity on the intracellular side
what uses kinase linked receptors
growth factors
which receptors cause myasthenia gravies
loss of Ach receptors
which receptors cause mastocytosis
increased c-kit receptor
how do nuclear receptors work
they are steroid receptors
work by modifying gene transcription
define ligand
a molecule that binds to another (usually larger) molecule
define agonist
a compound that binds to a receptor and activates it
