Biochemical Signalling

Question 1

What does activation of the a Gs, Gi and Gq type G-protein result in?

Answer 1

Gs activation = activation of adenylate cyclase, which functions to convert ATP to cAMP.

Gi activation = inhibition fo adenylate cyclase.

Gq activation = results in an increase in IP3 and intracellular calcium.

Question 2

In which subunit of G-proteins does GDP/GTP exchange occur?

Answer 2

GDP/GTP exchange occurs in the α-subunit.

Question 3

Which Phospholipase Cisoforms can be activated by G-proteins?

Answer 3

PLCβ - it contains a domain that allows it to interact with the Gα-subunit.

Question 4

What ion act as a cofactor for Phospholipase C beta (PLCβ)?

Answer 4

Ca2+

Question 5

What is the function of Phospholipase C (PLC)?

Answer 5

It functions to cleave PIP2 form the second messengers DAG and IP3.

Question 6

Name a ligand activator of Protein Kinase A.

Answer 6

cAMP - the binding of PKA causes the release and activation of its catalytic subunit.

Question 7

What is Gustducin and how is it activated?

Answer 7

Gustducin is a G-protein and is activated by the binding of a sweet-tasting molecule (S) to a sweet-taste receptor (SR).

Question 8

How does the Cholera toxin increase cAMP levels?

Answer 8

It causes an increase in cAMP levels as it leaves the G-protein locked in an activated state.