Together with nucleoporin alm1, tethers the proteasome to the nuclear envelope (PubMed:28974540, PubMed:11084332, PubMed:16096059). Involved in ubiquitin-mediated protein degradation and facilitates the degradation of nuclear proteins like mitotic cyclin and cut2 (PubMed:11084332, PubMed:16096059). Required for normal progression of anaphase (PubMed:8065367, PubMed:11084332). Binds the proteasome. The N-terminal part (residues 1 to 72) is polyubiquitinated by rhp6, which is required for the interaction with the proteasome. Belongs to the cut8/STS1 family.