L13: Activation and Inhibition of Proteins #1 Flashcards
These are harmful proteins.
Toxins/poisons
These are beneficial proteins.
Medicines/drugs
What are the 4 main steps of protein activation/inhibition?
1) chemical substance is present
2) chemical substance binds to target protein
3) causes activation or inhibition
4) changes to cellular response
This is the terminology for when a chemical substance interacts with its target protein
Binding/reception
These are compounds that bind to an enzyme and reduces its activity
Inhibitors
This controls chemical signalling between and within cells.
Receptor
These generally bind substrates to one active site. Changes substrates into product.
It can be membrane bound or free in the cytosol.
Enzymes
These have several binding sites that bind ligands. It usually releases ligand unchanged.
It can be membrane bound or free in the cytosol.
Receptors
_______ and __________ can be activated and inhibited and used as drug targets.
Enzymes; receptors
What are the 3 main classes of receptor?
1) ligand-gated ion channel
2) G-protein coupled receptor
3) receptor tyrosine kinase (RTK)
This is the general term given to a chemical substance that specifically binds to a receptor.
Ligand
True or false. Ligands can’t be proteins or large peptides.
False. Ligands range from small molecules, to large peptides and even proteins.
These are ligands that are produced in the body.
Endogenous ligands
These are ligands that come from the external environment. Examples are drugs and toxins.
Exogenous ligands.
True or false. Only some ligands make chemical contacts with their specific receptors.
False. All ligands make chemical contacts with their receptors.
This is known as the gate-keeper of cellular activity, controlling it from the cell surface.
Receptor
True or false. A ligand does not usually have to pass through the outer membrane when going from external to internal body environment.
True
True or false. Activation will only happen when ligands are not paired with their appropriate receptors.
False. Ligands have a specificity; meaning, activation/inhibition will only happen if the pairing between ligand and receptor is correct.
Why is binding to receptor proteins a significant process when making drugs?
Because having specific receptor proteins means that we can make drugs that bind only to certain receptor targets.
This is a chemical substance/ligand that binds to a receptor and activates it.
Agonist
When a receptor is activated, it will undergo a what to enable the function of the receptor?
A conformational shape change
This is the process where messages are passed on through the cell.
Signal transduction
True or false. Different receptors use the same types of relay molecules to pass on messages.
False. Different receptors use different relay molecules
Relay molecules - are molecules that relay the message to initiate cellular activity.
A chemical substance (ligand) that binds to a receptor and prevents activation by an agonist is called an..
Antagonist
True or false. Antagonist blocks the binding of an agonist; resulting in competition at the active site.
True. It occupies the active site first before the agonist to stop the agonist from binding
True or false. When an antagonist binds to an active site, signal transduction can still occur.
False. When the antagonist binds, the agonist can’t bind - which means that the enzyme will not be activated. If the enzyme is not activated, this means that signal transduction cannot occur.
Explain how adrenaline causes cellular changes.
1) Acts as an agonist to activate B-adrenergic receptor (a GPCR)
2) Signal transduction (causes activation)
3) Results in bronchodilation
What is the receptor adrenaline binds to? What kind of receptor is it?
B-adrenergic receptor. It is a GPCR receptor.
Are endogenous ligands more likely to be agonist or antagonist?
Agonist. Because they were already made in the body, so are specified to activate receptors in the body.
True or false. Ligand receptor interactions are non-specific.
False. They are highly specific; remember pairing can only occur between the right ligand and receptor pair - otherwise, activation will not occur.
Explain how insulin can cause cellular changes.
1) Insulin acts as an agonist to activate insulin receptor (RTK)
2) Signal transduction occurs.
3) Results in glucose uptake
What type of receptor does insulin bind to?
A RTK (insulin receptor)
Where are most receptors found on the cell?
The outside of the cell.
This is so they are able to detect extracellular changes and conduct messages on the inside to form the appropriate cellular responses.
