UPF3B (E5U4C) Rabbit mAb #56654

UPF3A and UPF3B are paralogs derived from a gene duplication and are involved in nonsense-mediated decay (NMD), a process that eliminates aberrantly formed mRNAs (1,2). While UPF3A seems to be an NMD repressor, UPF3B serves as an NMD activator, by binding to the exon junction complex (EJC) and shuttling to the cytoplasm after mRNA export (2-4). Under normal conditions, UPF3B will outcompete UPF3A binding to the EJC and key NMD factor UPF2, but upon UPF3B loss, UPF3A is upregulated and can become an NMD activator (4,5). UPF3 activation of NMD, however, can be independent of EJC binding (6). Though UPF3B is dispensable for global NMD, certain transcripts rely on it, suggesting there is both a UPF3B-dependent and independent pathway (7,8). UPF3B also plays a role in translation termination by causing dissociation of ribosomal complexes bound to mRNAs with premature termination codons (9). UPF3B can regulate differentiation of neural stem cells, and mutations and aberrant expression has been described in various neurological disorders, including autism and ALS (10-13).