Figure 1.

Co-immunoprecipitation of Bap31 with class I MHC molecules. A) Western blotting of Bap31 with mAb CC-1. Fully-assembled class I MHC from HeLa cells was serially immunoprecipitated with mAb KE2 (top row). Cleared supernatant (top row, right lane) possesses additional Bap31. Free class I heavy chains were serially immunoprecipitated with mAb HC10 (middle row); associated Bap31 was identified as for KE2. Bap31 also associates with free heavy chains in Daudi cells (bottom row). B) HeLa cells were transfected with constructs expressing the transmembrane and cytoplasmic domains of HLA-A2 fused to YFP (left), or with pA2-YFP-N3, which expresses the full-length HLA-A2 fused to YFP (right). YFP-tagged molecules were immunoprecipitated with anti-GFP antibody. Blots were probed with anti-GFP (top row, center row), or with CC-1 (bottom row). C) HeLa cells transfected with constructs expressing YFP-Bap31 (top row) or Bap31-YFP (bottom row). Class I was serially immunoprecipitated with KE2 and blots were probed with anti-GFP. Chimeric proteins run in proximity to a non-specific band (*) which may be IgH; this band is absent from whole-cell lysate (not shown) and cleared supernatant (right column).