Enables DNA-binding transcription activator activity, RNA polymerase II-specific and RNA polymerase II cis-regulatory region sequence-specific DNA binding activity. Involved in positive regulation of transcription by RNA polymerase II. Acts upstream of or within positive regulation of transcription, DNA-templated. Located in nucleus. Is expressed in several structures, including lens vesicle; myotome; nervous system; pancreas; and spleen. Used to study maturity-onset diabetes of the young and type 2 diabetes mellitus. Orthologous to human MAFA (MAF bZIP transcription factor A). [provided by Alliance of Genome Resources, Apr 2022]