Figure 8.
Inhibition of PDI complex formation by expression of GFP-PDI57. The aqueous phase of a Triton X-114 extraction was obtained from GFP-PDI57– and GFP-sec–expressing strains in the presence of 150 mM KCl, with or without 5 mM MgCl2, and subjected to gel filtration. (A and B) The elution profile of GFP-PDI57 showed the presence of three forms: two complexes of 450 and 150 kDa and the monomeric form of ∼35 kDa. (A and C) The elution profile of GFP-PDI57 extracted without MgCl2 revealed the absence of high-molecular-mass complexes. (A and D) The presence of PDI in high-molecular-mass complexes was inhibited by expression of GFP-PDI57. (A and E) The elution profile of GFP-sec showed its exclusive presence in the 30- to 35-kDa fractions. (A and F) The elution profile of PDI in extracts of GFP-sec–expressing cells showed the presence of high-molecular-mass complexes as in the wild-type strain (see Figure 6, B and C).