US2 expression leads to decreased synthesis and total level of HFE and HLA class I molecules.

293/HFE/US2 (clones 1-3) cells were metabolically labeled with³⁵[S]methionine for 1 hour, followed by sequential immunoprecipitation with anti-HFE Abs [αhHFE(2F5)] (2F5 followed by anti-HFE CT [αHFE (CT)]) and anti-TfR (αTfR) (A) or anti-HLA (αHLA) Abs (B). HFE/β2m complexes were detected by mAbs 2F5, free HFE heavy chains were detected with anti-HFE CT, and TfR-associated HFE complexes were detected with anti-TfR (V1-10) mAbs. HLA complexes were detected with W6/32, and free class I heavy chains were detected with anti-HLA HC. Cell lysates from HEK 293, 293/HFE, and 293/HFE/US2 were fractionated on SDS-PAGE (C) and analyzed by Western blot hybridization for the expression of total HFE (by anti-HFE CT), total HLA class I (by anti-HLA HC), and p53 (DO1).