FIGURE 3.

The role of the Pdi1p Cys⁹⁰-Cys⁹⁷ cysteine pair in the regulation of Ero1p. A, the redox states of DTT-reduced Pdi1p (redPdi1p) and GSSG-oxidized Pdi1p (oxPdi1p) proteins were monitored as described in the legend to Fig. 2A. The number of free thiols (-SH) in each Pdi1p protein was labeled on the right margin. B, the reduction of the regulatory disulfides in Ero1p C100A/C105A-FLAG by reduced Pdi1p proteins was monitored as described in the legend to Fig. 2B. C, the re-oxidation of the regulatory disulfides in reduced Ero1p C100A/C105A-FLAG at 0.5 μm was monitored at indicated times, with or without 10 μm oxidized Pdi1p proteins. D and E, the fraction of reduced Ero1p doublet in B and oxidized Ero1p species in C was quantified by densitometry and plotted against time (mean ± S.D., n = 3 independent experiments), respectively.