Enables several functions, including peptide antigen binding activity; protein antigen binding activity; and toxic substance binding activity. Involved in several processes, including B cell affinity maturation; cellular response to interferon-gamma; and positive regulation of T-helper 1 type immune response. Acts upstream of or within antigen processing and presentation of exogenous peptide antigen via MHC class II and immune response. Located in Golgi apparatus; endosome; and external side of plasma membrane. Is integral component of membrane. Part of MHC class II protein complex. Is expressed in lung; metanephros; and thymus primordium. Orthologous to human HLA-DQB2 (major histocompatibility complex, class II, DQ beta 2). [provided by Alliance of Genome Resources, Apr 2022]