Enables proteasome binding activity. Involved in several processes, including cellular response to electrical stimulus; hematopoietic or lymphoid organ development; and response to benzene. Located in cytosol. Part of proteasome complex. Biomarker of breast carcinoma and peptic esophagitis. Human ortholog(s) of this gene implicated in autoimmune disease (multiple); lymphoma; and renal cell carcinoma. Orthologous to human PSMB9 (proteasome 20S subunit beta 9). [provided by Alliance of Genome Resources, Apr 2022]