The figure shows nucleotide exchange on the alpha subunit of a heterotrimeric G protein during signal activation.
Which event activates the alpha subunit of a G protein?
- A
Methylation of the receptor's third cytoplasmic loop
- B
Phosphorylation of GDP to ATP
- Ccheck_circle
Exchange of GDP for GTP on the alpha subunit
- D
Removal of the gamma subunit by proteolysis
Explanation
Ligand-bound GPCRs catalyze GDP-to-GTP exchange on the alpha subunit. GTP-bound alpha then dissociates and binds downstream effectors such as adenylyl cyclase.