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DEXXQ-box helicase domain of UPF1 UPF1 (also called RNA Helicase And ATPase, Regulator Of Nonsense Transcripts, or ATP-Dependent Helicase RENT1) is an RNA-dependent helicase and ATPase required for nonsense-mediated decay (NMD) of mRNAs containing premature stop codons. It is recruited to mRNAs upon translation termination and undergoes a cycle of phosphorylation and dephosphorylation; its phosphorylation appears to be a key step in NMD. It is recruited by release factors to stalled ribosomes together with the SMG1C protein kinase complex to form the transient SURF (SMG1-UPF1-eRF1-eRF3) complex. In EJC-dependent NMD, the SURF complex associates with the exon junction complex (EJC) located downstream from the termination codon through UPF2 and allows the formation of an UPF1-UPF2-UPF3 surveillance complex which is believed to activate NMD. Diseases associated with UPF1 include juvenile amyotrophic lateral sclerosis and epidermolysis bullosa, junctional, non-Herlitz type. UPF1 is a member of the DEAD-like helicase superfamily, a diverse family of proteins involved in ATP-dependent RNA or DNA unwinding. This domain contains the ATP-binding region.
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