Acts as a transcriptional activator of a number of genes encoding proteasomal subunits. Binds to a PACE (proteasome-associated control element) DNA sequence 5'-GGTGGCAAA-3'. Its expression is in turn regulated by the 26S proteasome, thereby providing a negative feedback control mechanism. Required for normal growth at low temperatures. Probably interacts with SEC63. Interacts with MUB1, UBR2 and RPN2. Ubiquitinated by UBR2 in the presence of UBC2; which leads to proteasomal degradation. Mutants grow slowly at low temperatures and show partial mislocalization of nuclear antigens. According to PubMed:9512348, it is a component of the 26S proteasome.