basic FUNCTION
| key factor in both mRNA nuclear export and mRNA surveillance for the deletion of truncated messengers and initiation of nonsense mediated mRNA decay (NMD) |
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mediating the splicing of pre-mRNA by binding to the loop I region of U1-snRNA |
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acting as a nucleocytoplasmic shuttle |
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UPF3A levels are tightly regulated by a post-transcriptional switch to maintain appropriate levels of NMD substrates in cells containing different levels of UPF3B |
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UPF3B--is critical for the nonsense-mediated RNA decay (NMD) pathway, while its autosomal counterpart--UPF3A--encodes an enigmatic protein previously shown to have trace NMD activity |
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likely UPF3A acquired repressor activity through simple impairment of a critical domain, a rapid mechanism that may have been widely used in evolution |