In a G protein linked receptor signal transduction pathway, the G protein is activated when.....

Question

A. GTP binds to a subunit of the G protein
B. It becomes phosphorylated by protein kinases
C. Its ligand binds to it and the G protein is transported to the nucleus
D. GDP is formed from the hydrolysis of GTP

Answer 1

It would be A: GTP binds to a subunit of the G protein

In a G protein-coupled receptor pathway activation goes:

1. The binding of an extracellular ligand causes a conformational change in the receptor.
2. The receptor binds intracellularly to G protein.
3. Activated G protein binds GTP instead of GDP.
4. Three subunits of the G protein dissociate in a complex composed of β and γ subunits and the α subunit.