Fig. 4.
MHC II I-E associates with I-A in DC but not in B blasts. (A) Immunoprecipitations of 1% CHAPS lysates of B blasts and DCs were followed by SDS/PAGE and Western blotting for I-A. B blast lanes contain 2-fold the protein concentration of DC lanes to correct for amounts of MHC II. Lanes 1 and 2 illustrate 1% input of lysates used for IP. I-A lanes, IP with mAb 10-2.16; I-E lanes, IP with mAb 14.4.4S. (B) I-A (Left) and I-E (Right) expression on B blasts (green lines), immature DC (red lines), and mature DC (blue lines) by FACS. (C) DCs (lanes 2 and 4) or B blasts (lanes 1 and 3) were metabolically labeled with 35S, and after an overnight chase, I-A molecules were immunoprecipitated with mAb 10-2.16. Material was released from the beads by treating with Triton X-100, and I-E was recaptured from the IP with mAb 14.4.4S (lanes 1 and 2) or control IgGs (lanes 3 and 4), followed by SDS/PAGE and fluorography.