Core component of the HUSH complex, a multiprotein complex that specifically mediates epigenetic repression of mobile genetic elements, such as retroviruses and transposable elements (PubMed:26022416, PubMed:28581500, PubMed:29211708, PubMed:32976585, PubMed:33009411, PubMed:37433650). The HUSH complex represses LINE-1 (L1) retrotransposons that are still capable of transposition (PubMed:29211708, PubMed:32976585). Silencing events often occur within introns of transcriptionally active genes, and lead to the down- regulation of host gene expression (PubMed:29211708). The HUSH complex also represses exogenous retroviruses and synthetic transgenes (PubMed:26022416). The HUSH complex also represses expression of latent herpes simplex virus (PubMed:39589886). Mediates silencing of unintegrated retroviral DNA following recruitment by ZNF638: some part of the retroviral DNA formed immediately after infection remains unintegrated in the host genome and is transcriptionally repressed (PubMed:30487602). The HUSH complex is recruited to genomic loci rich in H3K9me3 and is required to maintain transcriptional silencing by promoting recruitment of SETDB1, a histone methyltransferase that mediates further deposition of H3K9me3, as well as MORC2, a chromatin remodeler that compacts chromatin (PubMed:26022416, PubMed:28581500). Within the HUSH complex, TASOR acts as the central scaffold which recruits MPHOSPH8 and PPHLN1 to mobile genetic elements and mediates association with SETDB1 and MORC2 (PubMed:32976585, PubMed:33009411, PubMed:39589886). The ability to silence mobile genetic elements plays a crucial role in early embryonic development: it is required to maintain epiblast cell fitness and cell division (By similarity). {ECO:0000250|UniProtKB:Q69ZR9, ECO:0000269|PubMed:26022416, ECO:0000269|PubMed:28581500, ECO:0000269|PubMed:29211708, ECO:0000269|PubMed:30487602, ECO:0000269|PubMed:32976585, ECO:0000269|PubMed:33009411, ECO:0000269|PubMed:37433650, ECO:0000269|PubMed:39589886}. This is the function of TASOR (transcription activation suppressor, Ensembl gene identifier ENSG00000163946).