Enables DNA-binding transcription factor activity, RNA polymerase II-specific; RNA polymerase II cis-regulatory region sequence-specific DNA binding activity; and RNA polymerase II-specific DNA-binding transcription factor binding activity. Involved in negative regulation of DNA-binding transcription factor activity; negative regulation of transcription by RNA polymerase II; and positive regulation of transcription from RNA polymerase II promoter involved in myocardial precursor cell differentiation. Acts upstream of or within several processes, including animal organ development; chordate embryonic development; and regulation of gene expression. Located in chromatin; cytoplasm; and nucleus. Is expressed in several structures, including egg cylinder; embryo mesenchyme; future spinal cord; heart; and mesoderm. Human ortholog(s) of this gene implicated in neural tube defect. Orthologous to human TBXT (T-box transcription factor T). [provided by Alliance of Genome Resources, Apr 2022]