Figure 3.
Folding status of the CH1 domain in unassembled truncated γ heavy chains. COS cells were transfected with cDNAs encoding the indicated genes. One dish expressing WT BiP and the truncated heavy chain was labeled in the presence of DTT to provide a marker for completely reduced heavy chain (lane 1). After 3 h of labeling, all dishes were washed twice and lysed in the presence of NEM and apyrase. The cell lysates (lanes 2, 3, 6, 7, and 8) and culture supernatant (lanes 4 and 5) were immunoprecipitated with the indicated antibodies or protein A-Sepharose alone (P.A.) and analyzed by SDS-PAGE under nonreducing conditions. The mobilities of the various folding intermediates are indicated.