A transmembrane protein begins with its N-terminus in the
cytosol and its C-terminus in the ER lumen. Vesicular trafficking
carries the protein to the Golgi, to the plasma membrane, back to
an endosome, and back to the plasma membrane. Where is the
C-terminus?
a. It was secreted along with the rest of the protein and
is diffusing away from the cell
b. It is in the plasma membrane, but it has 50% probability of
being in either orientation
c. It is at the extracellular surface of the cell
d. It is at the cytosolic surface of the plasma
membrane