UPF3B (Up-frameshift protein 3B) is a key component of the nonsense-mediated mRNA decay (NMD) machinery. It plays a critical role in recognizing and degrading transcripts containing premature termination codons (PTCs), thereby preventing the production of truncated proteins that could be toxic to cells[1].
UPF3B is a protein of approximately 483 amino acids with a molecular weight of ~56 kDa. Key structural features include:
| Property | Value |
|---|---|
| Gene | UPF3B |
| Protein Name | Up-frameshift protein 3B |
| UniProt | Q9Y5K8 |
| Molecular Weight | ~56 kDa |
| Length | 483 amino acids |
| Subcellular Localization | Nucleus, Cytoplasm |
| Protein Family | UPF3 family |
UPF3B is part of the SURF complex (Smg1, Upf1, Upf2, Upf3) that initiates NMD. Its normal functions include:
UPF3B and the NMD pathway have emerging connections to neurodegenerative diseases:
UPF3B mutations are associated with:
Lykke-Andersen S, et al. Structural basis for nonsense-mediated mRNA decay. The EMBO Journal. 2000. ↩︎
Bhattacharya A, et al. Nonsense-mediated mRNA decay in neuronal health and disease. Journal of Molecular Neuroscience. 2019. ↩︎
Tarpey PS, et al. Mutations in UPF3B, a member of the nonsense-mediated mRNA decay complex, cause mental retardation. Nature Genetics. 2007. ↩︎