FIG. 5.

Interactions of VacA-(Δ6–27) with c-myc-tagged s1/m1 VacA. c-myc-tagged VacA and nonbiotinylated VacA-(Δ6–27) could be readily distinguished by size differences in immunoblots using anti-VacA antiserum and an alkaline-phosphatase-conjugated secondary antibody (lanes a and b). As expected, the anti-c-myc antibody 9E10 immunoprecipitated c-myc-tagged VacA but not VacA-(Δ6–27) (lanes c to f). VacA-(Δ6–27) was successfully immunoprecipitated by the anti-c-myc antibody 9E10 if mixtures of c-myc-tagged VacA and VacA-(Δ6–27) were acid activated prior to the immunoprecipitation (lane g) but not in the absence of acid activation (lane h). +, present; −, absent.