Predicted to enable MHC class II protein complex binding activity and peptide antigen binding activity. Predicted to be involved in several processes, including antigen processing and presentation of exogenous peptide antigen via MHC class II; peptide antigen assembly with MHC class II protein complex; and positive regulation of T cell activation. Predicted to act upstream of or within antigen processing and presentation and immune response. Predicted to be located in membrane. Predicted to be part of MHC class II protein complex. Predicted to be active in late endosome membrane and lysosomal membrane. Human ortholog(s) of this gene implicated in several diseases, including asthma (multiple); autoimmune disease (multiple); bacterial infectious disease (multiple); hematologic cancer (multiple); and lung disease (multiple). Orthologous to several human genes including HLA-DOB (major histocompatibility complex, class II, DO beta); HLA-DPB1 (major histocompatibility complex, class II, DP beta 1); and HLA-DQB1 (major histocompatibility complex, class II, DQ beta 1).