Component of the HUSH complex, a multiprotein complex that mediates epigenetic repression. The HUSH complex is recruited to genomic loci rich in H3K9me3 and is probably required to maintain transcriptional silencing by promoting recruitment of SETDB1, a histone methyltransferase that mediates further deposition of H3K9me3. In the HUSH complex, contributes to the maintenance of the complex at chromatin (PubMed:26022416). Acts as a transcriptional corepressor and regulates the cell cycle, probably via the HUSH complex (PubMed:15474462, PubMed:17963697). The HUSH complex is also involved in the silencing of unintegrated retroviral DNA: some part of the retroviral DNA formed immediately after infection remains unintegrated in the host genome and is transcriptionally repressed (PubMed:30487602). May be involved in epithelial differentiation by contributing to epidermal integrity and barrier formation (PubMed:12853457).