Abstract The marsupial specific RSX lncRNA is the functional analogue of the eutherian specific XIST, which coordinates X chromosome inactivation.We strikketøy oppbevaring characterized the RSX interactome in a marsupial representative (the opossum Monodelphis domestica), identifying 135 proteins, of which 54 had orthologues in the XIST interactome.Both interactomes were enriched for biological pathways related to RNA processing, regulation of translation, and epigenetic transcriptional silencing.This represents a remarkable example showcasing here the functional coherence of independently evolved lncRNAs in distantly related mammalian lineages.