Where Is the Guanine Nucleotide-Binding Site of the G Protein $\alpha$

Multiple Choice

Where is the guanine nucleotide-binding site of the G protein located?

A) on the G _$\alpha$ subunit
B) on the G _$\beta$ subunit
C) on the G _$\gamma$ subunit
D) on the G _{$\beta$$\gamma$} subunit
E) on all three subunits