protein
| SMG8 binding to the SMG1:SMG9 complex specifically down-regulates the kinase activity of SMG1 on UPF1 without contacting the catalytic domain |
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SMG8 is involved in the recruitment of inactive SMG1 to the SURF complex |
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SMG1C (a complex containing SMG1, SMG8, and SMG9) contributes to regulate NMD by recruiting UPF1 and UPF2 to distinct sites in the vicinity of the kinase domain |
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SMG8 and SMG9 interact with the SMG1 C-insertion and promote high-affinity UPF1 binding to SMG1-8-9, as well as decelerated SMG1 kinase activity and enhanced stringency of phosphorylation site selection |
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SMG8 and SMG9 act, in addition to serving as a scaffold for the interaction between SMG1 and UPF1, to negatively regulate SMG1 kinase activity and maintain UPF1 in the unphosphorylated (inactive) form within the SURF complex |