Enables SMAD binding activity. Involved in several processes, including defense response to other organism; regulation of gene expression; and signal transduction by p53 class mediator. Acts upstream of or within several processes, including apoptotic signaling pathway; positive regulation of macromolecule metabolic process; and transmembrane receptor protein serine/threonine kinase signaling pathway. Located in PML body; cytosol; and nuclear matrix. Is extrinsic component of endoplasmic reticulum membrane. Colocalizes with heterochromatin. Is expressed in several structures, including alimentary system; brain; early conceptus; genitourinary system; and hemolymphoid system gland. Human ortholog(s) of this gene implicated in acute promyelocytic leukemia and skin cancer. Orthologous to human PML (PML nuclear body scaffold). [provided by Alliance of Genome Resources, Apr 2022]