Enables several functions, including histone deacetylase binding activity; identical protein binding activity; and methylated histone binding activity. Acts upstream of or within negative regulation of transcription, DNA-templated. Located in chromocenter; chromosomal region; and nucleolus. Part of histone deacetylase complex; histone methyltransferase complex; and transcription repressor complex. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; respiratory system; and sensory organ. Orthologous to human CBX5 (chromobox 5). [provided by Alliance of Genome Resources, Apr 2022]