Aquaporins are special channels made of protein and deposited into the cell membrane. Similar to a tunnel, they let molecules travel through them, entering or exiting the cell. Aquaporins are highly specific and let only water and nothing else pass through. 'Aquaporin' is therefore a great name for this protein, since 'aqua' means water and 'porin' means tunnel. Most cell membranes have many aquaporins, so the cell can react quickly to consistently maintain proper balance within the cell. Special Functions