2 Biological Signalling Molecules Flashcards
What are the 4 main types of signalling and how does each of them act?
- Autocrine: acts on itself
- Paracrine: Local mediator- acts of surrounding tissues
- Endocrine: Hormones released into bloodstream
- Synaptic: Neurotransmitter released into junction
What type of receptors are the family of nicotinic acetylcholine receptors?
Ligand gated ion channels
Are each of the following hydrophilic or hydrophobic?:
- Cell surface receptor
- Intracellular receptor
- Cell surface receptor: Hydrophilic
- Intracellular receptor: Hydrophobic
What is a Receptor?
Molecule that specifically recognises a second molecule - regulates a cellular process in response to ligand binding
Ligands can be either agonists or antogonists.
What’s the difference between them?
Agonist binds- produces activation
Antagonst binds- without causing activation
Out of the following 3 molecules, which has the highest binding affinity?
- Substrate
- Allosteric regulator
- Ligand
Ligand
How are receptors classified? (which factor) (2)
- Signalling molecules recognised
- Tightness of binding (affinity) of antagonists
What are two types of acetylcholine receptors?
- Nicotinic
- Muscarinic
What’s the difference between an acceptor and a receptor?
-
Receptor=
- silent at rest
- activated by agonist
-
Acceptor=
- operates in absence of ligand
- eg sodium channel
What are the 4 different types of receptors in terms of signal transduction?
- Membrane bound integral ion channels
- Membrane bound with integral enzyme activity
- Membrane bound coupled to effectors–> transducing proteins
- Intracellular receptors
Give an example of a receptor that is a:
Membrane bound integral ion channel
Nicotinic acetylcholine receptor
Channel opens
Sodium passes through
Gated pore
Give an example of a receptor that is a :
Membrane bound receptor with integral enzyme activity
Always work as dimers
Insulin receptor- linked to tyrosine kinase
Give an example of a receptor that is:
Membrane bound coupled to effectors–> transducing proteins
G protein-coupled receptors
- G proteins=
- GTP binding regulatory proteins
- Enzymes/channels
- 7 transmembrane domains
- eg M2 Muscarinic acetylcholine receptors- stimulates K+ channels
Provide an example of how intracellular receptors work
Hormone binds to receptor- causes conformational change to regulate gene expression
How can a G protein-coupled receptor amplify a signal?
One receptor binding- can cause activation of multiple G proteins
