Fig. 3.

ERp57 is sequestered in the conjugate. The conjugate does not undergo escape pathway mediated reduction. C1R cells expressing HLA-A*0201 and FLAG-tagged WT or C60A ERp57 were pulse-labeled for 45 min and chased for the indicated times before treatment with or without MMTS as indicated. Digitonin-solubilized cells were immunoprecipitated with PaSta1 (tapasin)- or Ox-68 (Ctrl)-coupled beads, and precipitated material was resolved by SDS/PAGE under reducing or nonreducing conditions. Bands corresponding to tapasin were quantitated, and the amount of free tapasin under nonreducing conditions was normalized to the total amount of tapasin present after reduction. The chart depicts the mean ± SEM of two independent experiments.