The nonsense-mediated mRNA decay (NMD) pathway is triggered upon assembly of the UPF surveillance complex near an exon junction complex (EJC). Cryo-EM studies have revealed the geometry of this transient assembly between the UPF complex and the EJC, which demonstrates how the UPF1 subunit elicits its RNA helicase activity toward the 3A end of the mRNA.
- Roberto Melero
- Gretel Buchwald
- Oscar Llorca