Enables ATP hydrolysis activity and transcription corepressor activity. Acts upstream of or within negative regulation of transcription by RNA polymerase II. Part of transcription regulator complex. Is expressed in several structures, including alimentary system; branchial arch; central nervous system; male reproductive gland or organ; and sensory organ. Orthologous to human ATF7IP (activating transcription factor 7 interacting protein). [provided by Alliance of Genome Resources, Apr 2022]