A.
A GTP-binding protein (G protein) is located on the cytoplasmic face of the plasma membrane.
B.
Gs proteins can activate their downstream effectors when bound by GTP and also have the ability to hydrolyze GTP.
C.
The activated G protein can change the activity of an enzyme.
D.
All of the above are correct (A, B and C)
E.
The activated G protein cannot change the activity of an ion channel