Enables DNA-binding transcription factor activity, RNA polymerase II-specific; identical protein binding activity; and nucleic acid binding activity. Involved in several processes, including osteoblast differentiation; positive regulation of transcription by RNA polymerase II; and transmembrane receptor protein serine/threonine kinase signaling pathway. Acts upstream of or within several processes, including animal organ development; osteoblast fate commitment; and positive regulation of macromolecule metabolic process. Located in cytoplasm and nucleus. Part of transcription regulator complex. Is expressed in several structures, including alimentary system; early conceptus; genitourinary system; nervous system; and sensory organ. Orthologous to human SMAD1 (SMAD family member 1). [provided by Alliance of Genome Resources, Apr 2022]