FIGURE 5.

Association of PDI with CTA1 after holotoxin disassembly. CT was appended to a SPR sensor slide coated with a polyclonal anti-CTA antibody, and a baseline measurement corresponding to the mass of the bound holotoxin was recorded. Reduced PDI (PDI + 1 mm GSH) was then perfused over the CT-coated sensor at 37 °C. PDI was removed from the perfusion buffer 400 s into the experiment and replaced with sequential additions of an anti-PDI antibody, an anti-CTB antibody, an anti-KDEL antibody, and an anti-CTA monoclonal antibody as indicated by the arrowheads. An identical result was obtained when CT was initially appended to a sensor slide coated with the monoclonal anti-CTA antibody and later detected with the anti-CTA polyclonal antibody.