DNA- and RNA binding protein, involved in several nuclear processes (By similarity). Binds the conventional octamer sequence in double-stranded DNA (By similarity). Also binds single-stranded DNA and RNA at a site independent of the duplex site (By similarity). Involved in pre-mRNA splicing, probably as a heterodimer with SFPQ (By similarity). Interacts with U5 snRNA, probably by binding to a purine-rich sequence located on the 3' side of U5 snRNA stem 1b (By similarity). Together with PSPC1, required for the formation of nuclear paraspeckles (By similarity). The SFPQ-NONO heteromer associated with MATR3 may play a role in nuclear retention of defective RNAs (By similarity). The SFPQ-NONO heteromer may be involved in DNA unwinding by modulating the function of topoisomerase I/TOP1 (By similarity). The SFPQ-NONO heteromer may be involved in DNA non-homologous end joining (NHEJ) required for double-strand break repair and V(D)J recombination and may stabilize paired DNA ends (By similarity). In vitro, the complex strongly stimulates DNA end joining, binds directly to the DNA substrates and cooperates with the Ku70/G22P1-Ku80/XRCC5 (Ku) dimer to establish a functional preligation complex (By similarity). NONO is involved in transcriptional regulation (By similarity). The SFPQ-NONO-NR5A1 complex binds to the CYP17 promoter and regulates basal and cAMP-dependent transcriptional activity (By similarity). NONO binds to an enhancer element in long terminal repeats of endogenous intracisternal A particles (IAPs) and activates transcription (By similarity). Regulates the circadian clock by repressing the transcriptional activator activity of the CLOCK-ARNTL/BMAL1 heterodimer (By similarity). Important for the functional organization of GABAergic synapses (By similarity). Plays a specific and important role in the regulation of synaptic RNAs and GPHN/gephyrin scaffold structure, through the regulation of GABRA2 transcript (By similarity). Plays a key role during neuronal differentiation by recruiting TET1 to genomic loci and thereby regulating 5-hydroxymethylcytosine levels (By similarity). Plays a role in the regulation of DNA virus-mediated innate immune response by assembling into the HDP-RNP complex, a complex that serves as a platform for IRF3 phosphorylation and subsequent innate immune response activation through the cGAS-STING pathway (By similarity). Monomer and component of the SFPQ-NONO complex, which is probably a heterotetramer of two 52 kDa (NONO) and two 100 kDa (SFPQ) subunits. NONO is a component of spliceosome and U5.4/6 snRNP complexes (By similarity). Interacts with CPNE4 (via VWFA domain) (By similarity). Forms heterodimers with PSPC1; this involves formation of a coiled coil domain by helices from both proteins. Part of complex consisting of SFPQ, NONO and MATR3. Part of a complex consisting of SFPQ, NONO and NR5A1. Part of a complex consisting of SFPQ, NONO and TOP1. Interacts with SPI1. Interacts with RNF43 (By similarity). Interacts with PER1 and PER2 (By similarity). Part of the HDP-RNP complex composed of at least HEXIM1, PRKDC, XRCC5, XRCC6, paraspeckle proteins (SFPQ, NONO, PSPC1, RBM14, and MATR3) and NEAT1 RNA. Interacts (via second RRM domain) with WASL; the interaction is direct. Component of a multiprotein complex with WASL and SFPQ (By similarity). Interacts with ERCC6 (By similarity). Interacts (via DNA-binding domain) with TET1 (By similarity). Continuously travels in and out of the nucleus. Localizes to stress granules in response to oxidative stress. A small subset localizes in mitochondria. The RRM domains can bind to both DNA and RNA. Hyperphosphorylated. Ubiquitinated.