β-AR Desensitisation

Question 1

G-protein inactivation

Answer 1

• G-alpha and B-gamma subunits will re-associate to inactive G protein shortly after dissociating

Question 2

Activation-dependent regulation

Answer 2

• Homologous desensitisation
• Gβγ binds activated GRK2
• GRK2 translocates and Pi’s the ligand-bound β-AR
• Only down-regulates activated receptors

Question 3

PKA

Answer 3

• Heterologous desensitisation
• PKA Pi’s β-ARs
• Whether receptor is activated or not

Question 4

Result of Pi-ing the β-AR

Answer 4

• β-arrestin binds Pi’d receptor

- Functionally uncouples β-AR and G protein