RNA-binding component of the HUSH complex, a multiprotein complex that mediates epigenetic repression of mobile genetic elements, such as retroviruses and transposable elements (PubMed:15474462, PubMed:17963697, PubMed:26022416, PubMed:32976585, PubMed:39658355). The HUSH complex mainly represses LINE-1 (L1) retrotransposons that are still capable of transposition (PubMed:32976585, PubMed:39658355). 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, as well as MORC2, a chromatin remodeler that compacts chromatin (PubMed:26022416). 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). Within the HUSH complex, PPHLN1 acts as a mRNA- binding component, which specifically binds nascent transcripts of mobile genetic elements, enabling HUSH-dependent silencing of transcripts (PubMed:39658355). Contributes to the maintenance of the HUSH complex at chromatin (PubMed:26022416, PubMed:39013473). As part of the HUSH2 complex, promotes epigenetic repression of interferon- stimulated genes (PubMed:33144593, PubMed:39013473). May be involved in epithelial differentiation by contributing to epidermal integrity and barrier formation (PubMed:12853457). {ECO:0000269|PubMed:12853457, ECO:0000269|PubMed:15474462, ECO:0000269|PubMed:17963697, ECO:0000269|PubMed:26022416, ECO:0000269|PubMed:30487602, ECO:0000269|PubMed:32976585, ECO:0000269|PubMed:33144593, ECO:0000269|PubMed:39013473, ECO:0000269|PubMed:39658355}. This is the function of Ensembl gene identifier ENSG00000134283 (PPHLN1, periphilin 1).