Activation and inhibition of proteins #1 Flashcards
How can proteins can be activated or inhibited by different substances to cause harm or have a positive health benefits?
Harmful substance - toxins or poisons
Beneficial substance - medicine or drugs
It’s the dose and route of administration of substrate that play a role in what effect it will have
What are some examples of substances that activate and inhibit proteins?
Antibiotics, alcohol, venom, fungi, hormones, neurotransmitters, drugs/medicine
What are the common steps of activating or inhibiting a protein?
Chemical substance travels from its source and interacts with its target protein (binding). This event affects the protein to either activate or inhibit it leading to functional consequences that can change the cellular response
What is a receptor?
Receptor is a cellular protein that controls chemical signalling between cells
1000 individual receptor proteins
Control many important physiological processes (sight, smell, taste)
About of 1/3 of all drugs target receptors
Can have several binding sites, bind ligand, release ligand unchanged, can be membrane bound or free in cytosol
What are the three classes of receptors?
Receptors are not all the same size or shape, there are three main classes which have different structures. The overall steps of activation and inhibition occur however the details differ
Three classes - ligand gated ion channel, G protein coupled receptor and receptor tyrosine kinase
What is a ligand?
A ligand is a chemical substance that specifically bind to a receptor, all ligands make chemical contacts with their specific receptors
Very diverse in chemical structure - range from small to large molecules
Endogenous ligands produced in body (endocrine hormone), exogenous ligand are produced outside body (drugs and toxins)
How do receptors bind to proteins?
Majority of receptors are found on the outer cell membrane - strategically important as they can act as sensors in extracellular environment and transmit signals into cell without actually entering cell (doesn’t need to pass through membrane). Controls cellular activity
What is specificity in ligand-receptor binding?
Specificity between ligands and receptors allows for ligands to control cellular activity. Activation or inhibition only will occur when receptor-ligand pairing is correct, used to make drugs that bind only to certain receptor targets
What is an agonist?
An agonist is a chemical substance that binds to a receptor and activates it. The receptor undergoes a conformational (shape) change to become activated. Produces the right number of chemical contacts not only to bind but to trigger a change in shape (changed from inactive to active receptor)
What is signal transduction?
Active receptor starts a chain of events where messages are passed through a cell via signal transduction
Different receptors use different molecules to ‘communicate’ these messages
What is an antagonist?
An antagonist is a chemical substance that binds to a receptor and prevents activation by an agonist - don’t produce chemical contact to change shape of receptor
Signal transduction does not occur as receptor remains inactive
