Figure 2.

Tailless A2 is stable in the presence of US2 and US11 while the endogenous class I heavy chains are destroyed. Cells were pulse labeled for 5 min and chased for the indicated times in the absence of proteasome inhibitors. US2-expressing cells (a), US11-expressing cells (b), or control cells (CC; c) transfected with tailless A2 (A2-cyt) were subjected to pulse–chase analysis. Immunoprecipitations were done with antibodies reactive with free heavy chains (αHC) or folded class I products (W6/32). The US2 and US11 molecules that coprecipitate in the W6/32 complex are indicated.