Enables DNA binding activity and DNA-binding transcription activator activity, RNA polymerase II-specific. Involved in several processes, including T-helper 1 cell lineage commitment; negative regulation of T-helper 17 cell lineage commitment; and regulation of gene expression. Acts upstream of or within T cell differentiation and positive regulation of isotype switching to IgG isotypes. Located in neuronal cell body and nucleus. Is expressed in several structures, including central nervous system; colon; genitourinary system; sensory organ; and thymus. Used to study asthma. Human ortholog(s) of this gene implicated in asthma, nasal polyps, and aspirin intolerance and immunodeficiency 88. Orthologous to human TBX21 (T-box transcription factor 21).