FIG. 2.

tBid is not present in the TNF-α-induced 500-kDa Bax protein complex. Cell lysates prepared in CHAPS lysis buffer were fractionated on a Sephacryl S-100 gel filtration column from cells treated as in Fig. 1. Column fractions 20 to 39 were analyzed by SDS-PAGE followed by Western blotting to Bax or E1B 19K, as indicated (A), or Bid (B). Whole-cell lysates from both the minus- and plus-TNF/CHX samples loaded on the column were included on every Western blot as an internal reference for Bax, E1B 19K, and Bid levels. The peaks at which the molecular weight markers fractionated are indicated.