“…When the wild type gene for ToxA has been expressed by Escherichia coli , various results have been achieved ranging from no secretion (Gray et al, 1984), periplasmic secretion (Lory et al, 1988) to extracellular secretion using an OmpA signal sequence substituted for that of the ToxA signal sequence (Chaudhary et al, 1988). Among the different chimeric proteins, TGFα-PE40 can be recovered from inclusion bodies, the periplasm, and supernatant when used with the OmpA signal sequence (Kondo et al, 1988), while PE35/TGFαKDEL was only found in inclusion bodies.…”