Enables DNA-binding transcription activator activity, RNA polymerase II-specific and RNA polymerase II intronic transcription regulatory region sequence-specific DNA binding activity. Involved in several processes, including animal organ morphogenesis; positive regulation of tongue muscle cell differentiation; and regulation of transcription by RNA polymerase II. Acts upstream of or within several processes, including animal organ development; regulation of transcription, DNA-templated; and vasculature development. Located in nucleus. Is expressed in several structures, including alimentary system; branchial arch; ear; embryo mesenchyme; and heart. Used to study DiGeorge syndrome; autism spectrum disorder; otitis media; and velocardiofacial syndrome. Human ortholog(s) of this gene implicated in DiGeorge syndrome; tetralogy of Fallot; and velocardiofacial syndrome. Orthologous to human TBX1 (T-box transcription factor 1). [provided by Alliance of Genome Resources, Apr 2022]