To determine the location of protein X in the plasma membrane, erythrocytes were subjected to two different treatments. First intact erythrocytes were treated with proteolytic enzymes. After the cells were lysed and membrane components extracted, protein X was intact. In the second experiment, the erythrocyte cells were permeabilized prior to treatment with proteolytic enzymes. When the plasma membrane components were then extracted, protein X was extensively fragmented What do these observations suggest about the location of protein X in the plasma membrane?
A. Proteolytic enzymes cannot fragment protein X in intact erythrocytes thus, protein Xis embedded in the lipid bilayer and does not have any extracellular domains
B. Since proteolytic enzymes cannot digest protein X uniess the plasma O o membrane is disrupted protein X is covalently attached to the inner leaflet of the lipid bilayer
C. Since proteolytic enzymes cannot digest protein X unless the membrane is disrupted protein X is polytopic and embedded in the lipid bilayer with several intracellular domains
D. Proteolytic enzymes cannot fragment protein X in intact erythrocytes therefore, protein X associates with the membrane transiently and is primarily located in the cytosol
E. Since proteolytic enzymes cannot fragment protein X in intact erythrocytes, protein X is tocated nside the cell and interacts with the inner surface of the membrane