You strip off all proteins on the cell surface by using a protease (an enzyme that destroys proteins). Now, when you add a specific signaling molecule, the cell still responds. Why is this?
A)The signaling molecule doesn't need a receptor.
B)The signaling molecule is polar and can diffuse into the cell.
C)The receptor is in the interior of the cell.
D)The signaling molecule is nonpolar and binds a cell-surface receptor.

Question

Quizplus · Accepted Answer

If the receptors have been destroyed by the protease, the only possible explanation is that the receptor is inside the cell, hence allowing the signaling molecule to enter the cell and bind to the intracellular receptor. Therefore, option C is the correct answer.

You Strip Off All Proteins on the Cell Surface by Using