Cell Signalling Flashcards
What are the 4 types of receptors
Ionotrophic receptor
G-coupled protein receptor
Enzyme linked receptor
Intracellular receptor
How ionotrophic receptor works
- Ligand binds to receptor
- Change protein channel- open pore
- Ion move in/out of cell via conc gradient
Examples of ionotrophic receptors
Ach (nicotinic Ach) receptor/ - ligand
On skeletal muscle
Cause muscle contraction
Or
GABA(A) receptor
How g-protein coupled receptor work
- Ligand binding changes receptor confirmation
- G-protein binds to receptor(GDP phosphorylated to GTP and exchanged)
- G-protein spit into 2 groups (a subunit (binds to target protein)/by subunit)
- A subunit- dephosphorylation GTP->GDP
- A subunit dissociate and inactive again.
- Receptor active as long as ligand bound
Types of G protein coupled receptors and their examples
- Gs (stimulation adenylyl cyclase) e.g. B1- adrenergic receptor
- Gi (inhibition adenylyl cyclase) e.g. M2-muscarinic receptor
- Gq (stimulates phospholipase c PLC) e.g. AT-1 angiotensin receptor
Example of Gs (stimulation) +how it works
B1- adrenergic receptor
ATP-> cAMP
cAMP activates PKA
Example of Gi (inhibition)
+how it works
M2-muscarinic receptor
Reduces level of PKA
Example Of Gq (stimulate phospholipid C PLC)
+how it works
AT-1 angiotensin receptor
IP3 -> Ca2+ release
/
PIP2
\
DAG activates PKC
Enyzme linked receptor +how it works
- Ligand bind
- Receptors clustering
- Activates enzyme activity in cytoplasm
- Phosphorylate receptor-> bind signalling protein
enzyme linked receptor and e.g
Insulin receptor
Ligand: insulin
Glucose uptake
Or
ErbB receptor
Ligand: epidermal growth factor/TGF B
Cell growth
Intracellular receptor
Type 1 cytoplasmic
+how it works
- In cytosol, with chaperone (Heat shock protein)
- Hormone bind to receptor. HSP dissociate.
- Form homodimer
- Translocates nucleus-> binds to DNA
Intracellular receptor
Type 2- nuclear
+how it works
- Located within nucleus
- Binding of hormone ligand-> transcriptional regulation
Intracellular receptor e.g.s
Type 1/type 2
Type 1- glucocorticoid receptor
Ligand- cortisol/corticosterone
Decrease immune response/increase gluconeogenesis
Type 2- thyroid hormone receptor
Ligand T3/T4
Growth and development
Examples of Endocrine communication
Insulin
Adrenaline
Glycogen
Examples of paracrine communication
Insulin
NO (vasodilate)
Osteoclast activating factor
