You are studying a new membrane protein called Protein X Pro

You are studying a new membrane protein called Protein X. Protein X can be extracted from erythrocyte membranes by concentrated salt solution. It can be cleaved into fragments by trypsin, but only when the membranes are disrupted. What type of membrane protein is protein X?

a. Integral

b. Peripheral

c. Integral, transmembrane

d. Lipid-linked

Solution

ANS: b. Peripheral

Explanation:

The protein X is a peripheral membrane protein because it is extracted from the disrupted erythrocyte membrane by using concentrated salt solution treatment.

Proteolytic treatment for disruption and extraction of erythrocyte membrane components can produce undigested and intact protein X.

The inability of the protease to digest the protein unless the membrane is disrupted suggests that protein X is likely bound to the inner surface of the corresponding cells plasma membrane, thus located internally.