Fig. 4.

Overview of the core NMD factors UPF1, UPF2, UPF3b/a, the kinase SMG1, and the decay inducing factors SMG5, SMG6, and SMG7. The domain architecture for all factors, as well as the NMD-specific functions of important regions are depicted here (for details, see text). The most studied isoforms of NMD factors were chosen for representation and match, except for SMG1, those indicated in Table 2 (see footnote b for SMG1 discrepancy). UPF1 phosphorylation sites (SQ and TQ motifs) verified by various experimental approaches (ultradeep HeLa cell phosphoproteome [222], in vitro phophorylation assay with UPF1 peptides [106] or full length UPF1 [154] ) are indicated. The phosphosites connected to specific recruiting functions are highlighted specifically