Molecular Basis of Drug Action Flashcards
what are nonspecific drugs?
drugs that act by physicochemical processes
what are specific drugs?
drugs that act on receptors, enzymes, transporters or other identified components of the cell
Which receptors regulate DNA transcription?
intracellular
describe what happens to membrane-bound receptors after a ligand binds.
They exist as monomer but after ligand binding, the conformation changes and two monomers dimerize and phosphorylate their partner and a tyrosine which then acts on another substrate
JAK/STAT are what kind of receptors?
membrane-bound
The acetylcholine receptor is an example of what type of receptor?
ligand-gated
A g-protein has a ____ bound to it, but switches this out for a ____ when ligand binds
GDP, GTP
The Gs alpha subunit causes what when activated?
an increase in Camp
The Gq subunit causes what when activated?
an increase in IP3, DAG and intracellular Ca++
What is the mechanism of short-term desensitization?
occurs via phosphorylation of serine and threonine residues in the receptor by G protein- coupled receptor kinases (GRKs)
When do receptors bind B-arrestin?
when the receptor is phosphorylated by GRKs
What is the mechanism of long-term desensitization?
occurs when receptors are trafficked to lysosomes and degraded
What are the assumptions of the Bimolecular Drug-Receptor reaction?
1) one drug molecule binds to one receptor
2) binding is reversible
3) D»R
4) there is a single class of noninteracting sites
5) Reaction is at steady-state
Low Kd means that there is a ______ affinity between drug and receptor
high
What is Kd?
the concentration of drug required to occupy 50% of its receptors
