Enables SUMO transferase activity and ubiquitin protein ligase binding activity. Involved in several processes, including fat cell differentiation; positive regulation of proteasomal ubiquitin-dependent protein catabolic process; and protein sumoylation. Located in nucleus. Colocalizes with PML body. Is expressed in several structures, including branchial arch; genitourinary system; sensory organ; tooth; and trunk mesenchyme. Orthologous to human PIAS1 (protein inhibitor of activated STAT 1). [provided by Alliance of Genome Resources, Apr 2022]