Ubiquitin-binding protein that plays a role in the modulation of innate immune response. Blocks both the RIG-I-like receptors (RLR) and NF-kappa-B pathways. Following viral infection, UBXN1 is induced and recruited to the RLR component MAVS. In turn, interferes with MAVS oligomerization, and disrupts the MAVS/TRAF3/TRAF6 signalosome. This function probably serves as a brake to prevent excessive RLR signaling (PubMed:23545497). Interferes with the TNFalpha-triggered NF-kappa-B pathway by interacting with cellular inhibitors of apoptosis proteins (cIAPs) and thereby inhibiting their recruitment to TNFR1 (PubMed:25681446). Prevents also the activation of NF-kappa-B by associating with CUL1 and thus inhibiting NF-kappa-B inhibitor alpha/NFKBIA degradation that remains bound to NF-kappa-B (PubMed:28152074). Interacts with the BRCA1-BARD1 heterodimer and regulates its activity. Specifically binds 'Lys-6'-linked polyubiquitin chains. Interaction with autoubiquitinated BRCA1 leads to the inhibition of the E3 ubiquitin-protein ligase activity of the BRCA1-BARD1 heterodimer (PubMed:20351172). Component of a complex required to couple deglycosylation and proteasome-mediated degradation of misfolded proteins in the endoplasmic reticulum that are retrotranslocated in the cytosol. Interacts with MAVS; this interaction prevents MAVS oligomerization and thus disrupts the RLR signaling pathway (PubMed:23545497). Interacts with CUL1; this interaction inhibits CUL1-mediated degradation of NF-kappa-B inhibitors (PubMed:28152074). Interacts with BIRC2/c-IAP1; this interaction prevents TNFalpha-stimulated RIP1 ubiquitination and subsequent NF-kappa-B activation (PubMed:25681446). Component of a complex required to couple retrotranslocation, ubiquitination and deglycosylation composed of NGLY1, SAKS1, AMFR, VCP and RAD23B. Interacts with HOMER2 (By similarity). Interacts directly with VCP. Interacts with BRCA1 and BARD1; interaction takes place when BRCA1 is not autoubiquitinated but is strongly enhanced in the presence of autoubiquitinated BRCA1. (Microbial infection) Interacts (via C-terminal UBX domain) with nipah virus protein V. The UBA domain specifically recognizes and binds 'Lys-6'-linked polyubiquitin chains.