Question

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

Answer 1

E

Step-by-step explanation:

Because it's a peripheral membrane protein it can not be embedded in the lipid bilayer.

Answer 2

B.

Explanation:

The cell membrane contains integral membrane proteins that are stably embedded into the phospholipid bilayer. These integral proteins are composed of hydrophobic amino acid residues that interact with fatty acyl groups of the phospholipid membrane. Consequently, the proteolytic enzymes cannot act against specific residues of the protein X when it is embedded in the cell membrane, but they can digest the protein when it does not interact with functional groups localized at the inner leaflet of the plasma membrane.