Nature Structural & Molecular Biology, Published online: 17 September 2026; doi:10.1038/s41594-026-01899-0The ATR–ATRIP kinase complex safeguards genome integrity by coordinating cellular responses to DNA damage and replication stress. Two recent cryo-EM studies resolve the structural basis of ATR–ATRIP activation, capturing distinct active states of the kinase and clarifying how its activity is stimulated by TOPBP1 and ETAA1.

Lau et al. report that Rrp12 coordinates ordered decoding center assembly during 40S biogenesis by promoting timely assembly factor release and preventing premature rRNA folding. Rrp12 C-terminal truncation disrupts decoding center maturation, triggering premature recruitment of the Rio1 kinase, which could be a nucleoplasmic checkpoint to monitor 40S assembly fidelity.

Lau et al. report that Rrp12 coordinates ordered decoding center assembly during 40S biogenesis by promoting timely assembly factor release and preventing premature rRNA folding. Rrp12 C-terminal trun...