Involved in the functional recruitment of the Sin3-histone deacetylase complex (HDAC) to a specific subset of N-CoR corepressor complexes. Capable of transcription repression by N-CoR. Active in deacetylating core histone octamers (when in a complex) but inactive in deacetylating nucleosomal histones. Component of the histone deacetylase complex that includes at least SIN3A, HDAC1 and HDAC2 (PubMed:9702189). Found in a complex composed of at least SINHCAF, SIN3A, HDAC1, SAP30, RBBP4, OGT and TET1 (PubMed:28554894). Interacts with HDAC1 (PubMed:9702189). Interacts with SIN3A, SIN3B, HDAC2, RBBP4 and NCOR1 (PubMed:9702189). Interacts directly with SAMSN1 (PubMed:20478393). Interacts with HCFC1 (By similarity). Interacts with SAP30BP (By similarity). Belongs to the SAP30 family.