What structures in the plasma membrane regulate ion passage?

The correct answer is integral membrane proteins.

Explanation:

The plasma membrane is the outer membrane of the cell which is selectively permeable. The small polar molecules and hydrophobic molecules can go through the lipid bilayer, but ions and large polar molecules cannot go through. There are some Integral membrane proteins present in the plasma membrane that enable ions to pass through the plasma membrane by active or passive transport.

Thus, the correct answer is integral membrane proteins. Ions generate electrochemical gradient so they are generally used in secondary transport systems.

Thus, the correct answer is integral membrane proteins.