Enables DNA-binding transcription activator activity, RNA polymerase II-specific; RNA polymerase II transcription regulatory region sequence-specific DNA binding activity; and chromatin 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. Part of transcription regulator complex. Is expressed in several structures, including foregut-midgut junction; genitourinary system; limb mesenchyme; lung; and neural tube. Orthologous to human RBPJL (recombination signal binding protein for immunoglobulin kappa J region like). [provided by Alliance of Genome Resources, Apr 2022]