Figure 4.

UPF2 co-immunopurifies with INT6 and eIF3. (A) A HeLa cell extract was processed as in Fig 2A, and the presence of UPF1 and UPF2 in the immunoprecipitates was analysed by immunoblotting. The same blot was successively probed with antibodies against UPF1 (top), UPF2 (middle) and INT6 (bottom). (B) A lysate as in (A) was immunoprecipitated with a goat serum (lane 1), a crude eIF3 antiserum (lane 2) and an antibody to eIF3b (lane 3). Immunoprecipitates were analysed by immunoblotting with antibodies to UPF2 (top), total eIF3 complex (middle) and eIF3b (bottom). IP, immunoprecipitation; PI, preimmune sera.