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 (By similarity). Core component of a SIN3A complex (composed of at least SINHCAF, SIN3A, HDAC1, SAP30, RBBP4, OGT and TET1) present in embryonic stem (ES) cells. Promotes the stability of SIN3A and its presence on chromatin and is essential for maintaining the potential of ES cells to proliferate rapidly, while ensuring a short G1-phase of the cell cycle, thereby preventing premature lineage priming (PubMed:28554894). Component of the Sin3/HDAC corepressor complex at least composed of BRMS1, BRMS1L, ING2, SAP30, SAP30L, HDAC1 (By similarity). Found in a complex composed of at least SINHCAF, SIN3A, HDAC1, SAP30, RBBP4, OGT and TET1. Interacts with SIN3A and OGT (PubMed:28554894). Embryonic stem cells (at protein level). Belongs to the SINHCAF family. Extended N-terminus.