Editing Tetanus (section)

=== Membrane translocation ===

The toxin then needs a way to get out of the vesicle and into the neuron cytosol for it to act on its target. The low pH of the vesicle lumen causes a conformational change in the toxin, shifting it from a water-soluble form to a [[Hydrophobe|hydrophobic]] form.<ref name=":1" /> With the hydrophobic patches exposed, the toxin can slide into the vesicle membrane. The toxin forms an [[ion channel]] in the membrane that is nonspecific for Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup>, and Cl<sup>−</sup> ions.<ref name=":0" /> There is a consensus among experts that this new channel is involved in the translocation of the toxin's light chain from the inside of the vesicle to the neuron cytosol, but the mechanism is not well understood or agreed upon. It has been proposed that the channel could allow the light chain (unfolded from the low pH environment) to leave through the toxin pore,<ref>{{cite journal | vauthors = Beise J, Hahnen J, Andersen-Beckh B, Dreyer F | title = Pore formation by tetanus toxin, its chain, and fragments in neuronal membranes and evaluation of the underlying motifs in the structure of the toxin molecule | journal = Naunyn-Schmiedeberg's Archives of Pharmacology | volume = 349 | issue = 1 | pages = 66–73 | date = January 1994 | pmid = 8139702 | doi = 10.1007/BF00178208 | s2cid = 9398335 }}</ref> or that the pore could alter the [[electrochemical gradient]] enough, by letting in or out ions, to cause osmotic lysis of the vesicle, spilling the vesicle's contents.<ref>{{cite journal | vauthors = Cabiaux V, Lorge P, Vandenbranden M, Falmagne P, Ruysschaert JM | title = Tetanus toxin induces fusion and aggregation of lipid vesicles containing phosphatidylinositol at low pH | journal = Biochemical and Biophysical Research Communications | volume = 128 | issue = 2 | pages = 840–9 | date = April 1985 | pmid = 3994725 | doi = 10.1016/0006-291X(85)90123-8 }}</ref>