JC3: Signalling, receptors, and pharmacology (3)

Question 1

Describe the stimulation of adenylyl cyclase

Answer 1

1. An agonist binds to the GPCR
2. There is GTP-for-GDP exchange which results in an active α_s-GTP complex
3. This causes an increase in enzymatic activity
4. ATP is converted to cyclic AMP which activates cyclic AMP-dependent protein kinase (PKA) and adenylyl cyclase

Question 2

Describe the inhibition of adenylyl cyclase.

Answer 2

1. An agonist binds to the GPCR
2. There is GTP-for-GDP exchange which results in an active α_i-GTP complex
3. This causes an decrease in enzymatic activity
4. ATP is not converted to cyclic AMP so cyclic AMP-dependent protein kinase (PKA) and adenylyl cyclase are not activated

Question 3

How does cyclic AMP exert the majority of its actions?

Answer 3

Through cyclic AMP-dependent protein kinase (PKA)