Tight junctions were once thought to have been an impermeable “grout”, keeping all but the smallest of molecules away from the immune system on the other side of the cellular barrier.
However, we now know that zonulin a protein produced by intestinal epithelial cells and by cells in other organs where tight junctions also occur, increases permeability by loosening these tight junctions to allow movement of not only small molecules but also large molecules and immune system cells between body compartments.
In this tutorial you will find out how a failed experiment to find a vaccine for cholera lead to the discovery of zonula occludens toxin [Zot] and ultimately to zonulin, a discovery that revolutionized how we viewed the function of tight junctions.
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