13 Flashcards
Common steps leading to changes in cellular response
• Chemical substance (drug, hormone, etc) travels from its source.
– e.g. ingested drug or toxin, endocrine hormone from a gland, neurotransmitter from a neuron, injected drug
• Chemical substance interacts with its target protein – this is called binding or reception* (this is where the proton receives the substance)
• The binding event affects the protein to either activate or inhibit it.
• This leads to functional consequences, that change the cellular response
What is a receptor?
A cellular protein (or assembly of proteins) that control chemical signalling between and within cells is called a receptor
How many individual receptor proteins are there?
1000
What do receptors control?
Receptors control many important physiological processes,
including sight, smell & taste, heart rate, neurotransmission
How many drugs activate or inhibit receptors
1/3
Compare and contract enzymes and receptors
Enzymes:
• Generally one active site.
• Bind substrates.
• Change substrate into product.
• Can be membrane bound or free in cytosol
Receptors:
• Can have several binding sites.
• Bind ligands.
• Release ligand unchanged.
• Can be membrane bound or free in cytosol.
Both can be activated and inhibited, and used as drug targets.
Three main classes of receptor
Differences and similarities off receptor classes
• They have different structures
• The same overall steps of activation and inhibition occur
for all receptors, though the exact details differ.
What is a ligand?
The general term given to a chemical substance that specifically binds to a receptor is a ligand.
Ligands are very diverse in chemical structure,
ranging from small molecules to large peptides
and even proteins
Ligands are very diverse in chemical structure,
ranging from small molecules to large peptides
and even proteins
Endogenous ligands
- produced in the body
Exogenous Logan’s
Drugs and toxins
All ligands make chemical contacts with their
specific receptors.
All ligands make chemical contacts with their
specific receptors.
Where are recepotrs found?
Most receptors are found on the outer cell
membrane, where they act as sensors of the
extracellular environment
Does Ligans pass through membrane?
Not usually
The reception is a ____ of ______, controlling it from ______
The receptor is a “gate-keeper” of cellular
activity, controlling it from the cell surface.
What are responses to extracellular rituals procured by
Intracellular responses to extracellular
signals can be produced by a membrane
receptor being activated
There is _____ between Logan’s and receptors
Specificity
Activation or inhibition will only happen whe.
Pairing is correct
Specificity concept
The process of binding to receptor proteins specifically is used to make…
Drugs that bind to only certain receptor targets
What is an agonist
A chemical substance (ligand) that binds to a receptor and activates it is called an agonist.
What happens for recepor activation
- receptor usually just sitting on membrane
- agonist binds - make enough chemical contracts to causes a conformational change
- allows to make an inside change even tho bound from outseides
What is an antagonist
A chemical substance (ligand) that binds to a receptor and prevents activation by an agonist is called an antagonist
- stops agonist from bindinding - inhibiting cellular response
- signal trnaducting therfore doesn’t occur
LOTS OF EXOGENOUS DRUGS ARE ANTAGONISTS
Comparing agonist and antogonist - NOT EXAMINABLE
• Both make specific chemical contacts with receptors • Often bind in a similar position but the chemical contacts
made by an agonist are sufficient to cause a conformational
change – both are keys for the same lock but only the
agonist can open it
- both are occupying same binding pocket in the same position
- chemical contacts make by against triggers conformational change unlike antagonist
Activation and inhibition of proteins
Inhibition of cellular response diagram
Ligand, agonist and antagonist definitions
Examples of signal transduction
What happens after a conformational change has occurred and receptor is acitvated?
- active receptor starts a chain of events where messages are passed on through the cell via a process called signal transduction
- different receptors use different types of relay molecules to pass on messages
How medical chemists produce safe and effective medicines
Medicinal chemists often start with the chemical structure of
an endogenous ligand, making new molecules from this to
produce safe and effective medicines.
