Promotes the cis-splicing and editing of several mitochondrial RNAs (including NAD5 transcripts) (PubMed:28549172). Plays a role in RNA transcription or processing during stress. Binds RNAs and DNAs sequence with a preference to single-stranded nucleic acids. Displays strong affinity to poly(U) sequence. Exerts cold and freezing tolerance, probably by exhibiting an RNA chaperone activity during the cold and freezing adaptation process. Mediates cell-to-cell trafficking of RNA interference (RNAi) signals (small RNAs (sRNA), e.g. small interfering RNA (siRNA) and microRNA (miRNA)) which regulate growth and development, as well as responses to environmental inputs, including pathogen attack; can compromise zucchini yellow mosaic virus (ZYMV) and tobacco rattle virus (TRV) infections at the early stage (PubMed:31812689). Binds to small phloem-mobile single-stranded RNAs (ss-sRNA, e.g. small interfering RNA (siRNA) and microRNA (miRNA)) in the phloeme exudate, including viral-derived sRNA (vsiRNA) (PubMed:31812689). Interacts with ORRM2, RBG3/ORRM3 and RBG5/ORRM4 (PubMed:28549172). Observed in the phloem translocation stream. A number of isoforms are produced. According to EST sequences. Up-regulated by cold stress and down-regulated by dehydration stress. Induced by hydrogen peroxide (at the protein level). The glycine-rich (GR) domain is necessary and sufficient for cell-to-cell movement and to interefere with zucchini yellow mosaic virus (ZYMV) infection. The RRM domain is required to promote mitochondrial RNA processing. Defects in seed germination under salt or cold stress (PubMed:17376161). Altered seedling growth under cold stress (PubMed:17376161). Delayed growth and late flowering associated with reduced mitochondrial RNA editing efficiency, including the cis-splicing of the first intron of the NAD5 transcript (PubMed:28549172). The triple mutant srbp1 srbp2 srbp3 is more susceptible to tobacco rattle virus (TRV) (PubMed:31812689). Plants overexpressing RBG2 confer freezing tolerance. Belongs to the GR-RBP family. Sequencing errors.