Molecular Pharmacology Flashcards
What is molecular classification of receptors?
Identify and sequence cDNA to predict the AA sequence. Repeat for all subtypes to give comparison my molecular classification. May identify new subtypes.
Methods to reveal receptor subtypes? Least-most
Protein purification and cDNA cloning
Homology cloning
(EST) expressed sequence tags
Genome data mining
What is a G-protein-coupled receptor?
A seven transmembrane receptor that binds extra cellular substances and transmits signal to an intracellular molecule G protein.
How does a G protein coupled receptor work?
First an extra cellular ligand binds causing a confirmations change to the trimmer alpha beta gamma subunits. The GDP bound to alpha swaps and become GTP causing active forms to be taken. Alpha+GTP and Beta+Gamma.
What does active form Alpha+GTP cause?
It effects effector enzymes such as adenylyl cyclase.
What does the beta gamma subunit effect?
Ion channels and kinases
Which subunit attaches to the membrane in a GCP?
Gamma is attached by a fatty acid chain
What are ligand gated ion channels?
Channels that allow the flow of ions into the cell in response to binding of a chemical messenger to its respective receptor.
What do ligand gated ion channels look like?
They are oligomeric receptors made up of 5 subunits that associate. Can be either homo or Hetero oligomeric.
What is ligand gated ion channels transduction mechanism?
Binds agonist causing a conformational change. They then select specific ions to flux through membrane.
How is a ligand gated ion channel organised?
Each ion channel has 4 subunits named. M1-4 and M2 is very important.
Why is M2 subunit so important in ligand gated ion channels?
It’s close to the centre of the channel and forms the gate that ions pass through.
What subunits make a ligand gated ion channel?
5 subunits: 2 alpha ,sigma,gamma and beta
Where does acetylcholine bind on ligand gated ion channels?
It’s bind majorly to the alpha subunits and minorly to the neighbouring non alpha subunits.
What are the key features of M2?
Hydrophobic amino acids with growing larger R groups towards bottom
Hydroxylated aminos desaturate ions (remove water)
Charged amino acid complementary to the ion charge allow flow
What happens when ligand bind the ion channel?
When agonist binds N-terminal domain twists levering the M2 domain to cause it to form an open confirmation
What are tyrosine linked receptors?
Single transmembrane domains that dimerise leading to phosphorylation that leads to intracellular recruitment of proteins that lead to downstream signalling.
What is the tyrosine kinase transduction mechanism?
Activated by Ligand binding causing a conformational change and dimerisation. The dimerisation activates intrinsic tyrosine kinases and creates a site for phosphotyrosine or SH2 binding sites
What are steroid receptors?
Class of molecules that when activated act as both signal transducers and transcription factors
What is steroid receptors transduction mechanism?
Steroid binds receptors causing them to diffuse into the cell and bind HSP-90 receptors dimerise and release HSP-90 then bind to DNA activating transcription
What is pharmagenomics?
How genetic variation effects the way in which a drug works. Controlled to ensure efficacy and reduce side effects
Cytochrome P450 does what?
It performs oxidation reaction that cause detoxifying.
How does Cytochrome P450 cause detoxifying?
- increase elimination
- inactivate/reduce potency
- generate toxic intermidiate
What genomic changes can you have for cytochrome P450?
Gene deletion
Single copy
Gene duplication
How does gene deletion effect metabolism?
No mRNA made so no enzyme meaning no metabolism
How does a single copy effect metabolism?
- unstable enzyme -decrease
- stable enzyme - normal
- altered enzyme- other metabolites
How does duplication of Cytochrome P450 gene effect metabolism?
Higher enzyme levels so increased drug metabolism
