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Protein UPF3B PDB 1uw4.png
Available structures
PDB Human UniProt search: PDBe RCSB
Aliases UPF3B, HMRX62, MRXS14, RENT3B, UPF3X, Upf3p-X, UPF3BP1, UPF3BP2, UPF3BP3, UPF3 regulator of nonsense transcripts homolog B (yeast)
External IDs MGI: 1915384 HomoloGene: 11307 GeneCards: UPF3B
RNA expression pattern
PBB GE UPF3B 218757 s at fs.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr X: 119.81 – 119.85 Mb Chr X: 37.09 – 37.11 Mb
PubMed search [1] [2]
View/Edit Human View/Edit Mouse

Regulator of nonsense transcripts 3B is a protein that in humans is encoded by the UPF3B gene.[3][4][5]

This gene encodes a protein that is part of a post-splicing multiprotein complex involved in both mRNA nuclear export and mRNA surveillance. The encoded protein is one of two functional homologs to yeast Upf3p. mRNA surveillance detects exported mRNAs with truncated open reading frames and initiates nonsense-mediated mRNA decay (NMD). When translation ends upstream from the last exon-exon junction, this triggers NMD to degrade mRNAs containing premature stop codons. This protein binds to the mRNA and remains bound after nuclear export, acting as a nucleocytoplasmic shuttling protein. It forms with Y14 a complex that binds specifically 20 nt upstream of exon-exon junctions. This gene is located on the long arm of chromosome X. Two splice variants encoding different isoforms have been found for this gene.[5]


UPF3B has been shown to interact with UPF2[4][6][7][8] and UPF1.[4][7][9]


  1. ^ "Human PubMed Reference:". 
  2. ^ "Mouse PubMed Reference:". 
  3. ^ Serin G, Gersappe A, Black JD, Aronoff R, Maquat LE (Jan 2001). "Identification and characterization of human orthologues to Saccharomyces cerevisiae Upf2 protein and Upf3 protein (Caenorhabditis elegans SMG-4)". Mol Cell Biol. 21 (1): 209–23. doi:10.1128/MCB.21.1.209-223.2001. PMC 88795Freely accessible. PMID 11113196. 
  4. ^ a b c Lykke-Andersen J, Shu MD, Steitz JA (Feb 2001). "Human Upf proteins target an mRNA for nonsense-mediated decay when bound downstream of a termination codon". Cell. 103 (7): 1121–31. doi:10.1016/S0092-8674(00)00214-2. PMID 11163187. 
  5. ^ a b "Entrez Gene: UPF3B UPF3 regulator of nonsense transcripts homolog B (yeast)". 
  6. ^ Lehner, Ben; Sanderson Christopher M (Jul 2004). "A protein interaction framework for human mRNA degradation". Genome Res. United States. 14 (7): 1315–23. doi:10.1101/gr.2122004. ISSN 1088-9051. PMC 442147Freely accessible. PMID 15231747. 
  7. ^ a b Lejeune, Fabrice; Li Xiaojie; Maquat Lynne E (Sep 2003). "Nonsense-mediated mRNA decay in mammalian cells involves decapping, deadenylating, and exonucleolytic activities". Mol. Cell. United States. 12 (3): 675–87. doi:10.1016/S1097-2765(03)00349-6. ISSN 1097-2765. PMID 14527413. 
  8. ^ Lykke-Andersen, Jens (Dec 2002). "Identification of a human decapping complex associated with hUpf proteins in nonsense-mediated decay". Mol. Cell. Biol. United States. 22 (23): 8114–21. doi:10.1128/MCB.22.23.8114-8121.2002. ISSN 0270-7306. PMC 134073Freely accessible. PMID 12417715. 
  9. ^ Schell, Thomas; Köcher Thomas; Wilm Matthias; Seraphin Bertrand; Kulozik Andreas E; Hentze Matthias W (Aug 2003). "Complexes between the nonsense-mediated mRNA decay pathway factor human upf1 (up-frameshift protein 1) and essential nonsense-mediated mRNA decay factors in HeLa cells". Biochem. J. England. 373 (Pt 3): 775–83. doi:10.1042/BJ20021920. ISSN 0264-6021. PMC 1223536Freely accessible. PMID 12723973. 

Further reading[edit]