Subunit of the Sin3 deacetylase complex (Sin3/HDAC), this subunit is important for the repression of genes encoding components of the TGF-beta signaling pathway. Core component of a SIN3A complex (composed of at least SINHCAF, SIN3A, HDAC1, SAP30, RBBP4, OGT and TET1) present in embryonic stem (ES) cells and is essential to maintain the complex on chromatin. Component of the Sin3/HDAC corepressor complex at least composed of BRMS1, BRMS1L, ING2, SAP30, SAP30L, HDAC1. Found in a complex composed of at least SINHCAF, SIN3A, HDAC1, SAP30, RBBP4, OGT and TET1. Belongs to the SINHCAF family.