7 - Transmembrane Receptors Flashcards
What are transmembrane receptors?
Transmembrane receptors are proteins that span the
thickness of the plasma membrane of the cell
Where is the transmembrane receptor in relation to the cell?
One end of the receptor is outside (extracellular domain)
and one end is inside (intracellular domain) the cell
What three sections of the receptor are there?
- extracellular - discriminator domain with ligand binding site
- transmembrane - transmembrane domain
- intracellular - effector domain
What three types of transmembrane receptors are there?
- protein kinase-coupled receptor
- G-protein-coupled receptor
- ion channel-coupled receptor
What effector domains do the three transmembrane receptors have?
- protein kinase-coupled receptor - 2 PK domains
- G-protein-coupled receptor - G protein
- ion channel-coupled receptor - none
What are drugs?
Drugs are receptor modulators and do not confer
new properties on cells and tissues
What can drugs do?
Drugs can enhance, diminish or block the generation,
transmission or receipt of a ligand-generated
signal by several mechanisms
How is the action of a drug classified?
The action of a drug is classified according to whether
it produces (agonist) or diminishes (antagonist)
the signal
What are the action pathways of drugs on receptors?
- input signal activates the ANTAGONIST, which interacts with the discriminator domain of the receptor, which is attached for the effect domain
- input signal activates the AGONIST, which interacts with the discriminator domain of the receptor, which is attached for the effect domain
- there is a highly specific, non covalent interaction according to the lock-key principle (structural complementarity)
- this may affect various signalling pathways
-output signals are generated
What drugs antagonise. block, or inhibit endogenous proteins? (6)
- Antagonists of Cell Surface Receptors
- Antagonists of Nuclear Receptors
- Enzyme Inhibitors
- Ion Channel Blockers
- Transport Inhibitors
- Inhibitors of Signal Transduction Proteins
What drugs activate endogenous proteins?
- Agonists of Cell Surface Receptors
- Agonists of Nuclear Receptors
- Enzyme Activators
- Ion Channel Openers
How do drugs use sites on the receptor? (agonists and antagonists, allosteric agonists and antagonists, and other drugs)
- Agonists and antagonists compete with
hormones/neurotransmitters for binding sites - Allosteric agonists or antagonists enhance or
block the signal by binding to allosteric sites
that influence signal transmission - Other drugs can block signal transduction
within the membrane or at intracellular signal
reception points
What mechanisms are used for the recognition of a drug or hormone by a receptor?
The recognition of a drug or hormone by a receptor
uses non-covalent mechanisms, such as hydrogen
bonds, electrostatic forces, hydrophobic and Van der
Waals forces
What chemical bonds are involved in drug actions (from strongest of weakest)?
- covalent
- ionic
- hydrogen
- hydrophobic
- van der Waals
Properties of most drug-receptor interactions
- reversible
- weak chemical bonds
