Predicted to enable proteasome binding activity. Acts upstream of or within antigen processing and presentation and response to bacterium. Part of proteasome core complex and spermatoproteasome complex. Is expressed in thymus primordium. 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]