Figure 4.

PR and TR proteins are not the target of the ubiquitin–proteasome pathway. (A) ³⁵S-labeled PR protein was incubated with ATP and ubiquitin either in the absence of UBA/UBCs or in the presence of UBA and UBCs for 120 min (UbcH5B and UbcH7). In the presence of UBA/UBCs, the reaction mixtures were treated with either vehicle or 33 μM MG132. The position of intact PR is indicated by the arrow. (B) ³⁵S-labeled TR was incubated with ATP and ubiquitin either in the absence of UBA/UBCs or in the presence of UBA and UBCs for 120 min (UbcH5B and UbcH7). The reaction mixtures containing UBA and UBCs were treated with either vehicle or 33 μM MG132. The position of intact TR is indicated by the arrow.