(A) Structure of human TXNDC11 is schematically shown with cysteine residues (C) highlighted together with their positions. (B) Cell lysates were prepared from WT, EDEM2-KO, and TXNDC11-KO cells expressing WT or one of various cysteine mutants of 3x Flag-tagged TXNDC11 together with Myc-tagged EDEM2 by transfection, subjected to SDS-PAGE under non-reducing conditions, and analyzed by immunoblotting using anti-TXNDC11 and anti-EDEM2 antibodies. (C) Cell lysates were prepared from TXNDC11-KO cells expressing WT or one of the three cysteine mutants of 3x Flag-tagged TXNDC11, and subjected to immunoprecipitation using anti-Flag antibody. An aliquot of cell lysates (Input) and the immunoprecipitates {IP(Flag)} were subjected to SDS-PAGE under reducing conditions, and analyzed by immunoblotting using anti-EDEM2 and anti-TXNDC11 antibodies. (D) Cell lysates were prepared from WT, EDEM2-KO, and TXNDC11-KO cells expressing WT or one of the three cysteine mutants of 3x Flag-tagged TXNDC11 together with mCD3-δ-ΔTM-HA by transfection, and analyzed by immunoblotting using anti-HA and anti-TXNDC11 antibodies. (E) Cycloheximide chase was conducted to determine the degradation rate of mCD3-δ-ΔTM-HA in WT and TXNDC11-KO cells expressing WT or one of the three cysteine mutants of 3x Flag-tagged TXNDC11 by transfection, and cell lysates were analyzed by immunoblotting using anti-HA antibody (n = 3). Quantified data are shown on the right.