Enables DNA-binding transcription repressor activity, RNA polymerase II-specific; RNA polymerase II transcription regulatory region sequence-specific DNA binding activity; and identical protein binding activity. Involved in negative regulation of transcription by RNA polymerase II. Acts upstream of or within several processes, including adult feeding behavior; adult locomotory behavior; and brain development. Part of transcription regulator complex. Is expressed in several structures, including alimentary system; central nervous system; embryo ectoderm; limb bud; and sensory organ. Orthologous to human DMBX1 (diencephalon/mesencephalon homeobox 1). [provided by Alliance of Genome Resources, Apr 2022]