PT - JOURNAL ARTICLE AU - Andrew B. Maksymowych AU - Lance L. Simpson TI - Structural Features of the Botulinum Neurotoxin Molecule That Govern Binding and Transcytosis across Polarized Human Intestinal Epithelial Cells AID - 10.1124/jpet.104.066845 DP - 2004 Aug 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 633--641 VI - 310 IP - 2 4099 - http://jpet.aspetjournals.org/content/310/2/633.short 4100 - http://jpet.aspetjournals.org/content/310/2/633.full SO - J Pharmacol Exp Ther2004 Aug 01; 310 AB - Experiments were done to help localize the minimum essential domain within the botulinum toxin molecule that is necessary for binding and transport across human gut epithelial cells. The data demonstrated that the neurotoxin alone, in the absence of auxiliary proteins, undergoes transcytosis. The neurotoxin by itself was examined in the single chain (unnicked serotype B) and dichain (nicked serotype B, nicked serotype A) forms, and all displayed the ability to bind and penetrate epithelial barriers. In addition, the single chain and dichain molecules were examined in the oxidized and reduced states, and again all forms were transported. To further define the minimum essential domain, experiments were done with two toxin fragments: 1) the heavy chain, which was derived from native toxin, and 2) the carboxy-terminal portion of the heavy chain, which was generated by recombinant techniques. Interestingly, both fragments were fully competent in crossing epithelial barriers. These data suggest that a polypeptide derived from the toxin could be used as a carrier domain to transport other molecules across epithelial cells. In related experiments, physiological (i.e., potassium depletion) and pharmacological (i.e., chlorpromazine) manipulations were used to implicate clathrin-coated pits/vesicles as the structures responsible for endocytosis of toxin. The American Society for Pharmacology and Experimental Therapeutics