Those weird fibers in mammal embryos are actually huge factories that tag proteins for the rest of the body.
March 25, 2026
Original Paper
In situ cryo-ET of mammalian embryos reveals cytoplasmic lattices contain ubiquitin-charged E2-E3 ligase assemblies
bioRxiv · 10.64898/2026.03.22.713481
The Takeaway
For 60 years, scientists have observed 'cytoplasmic lattices' in early embryos without knowing what they actually do. High-resolution imaging finally reveals they are giant molecular machines that tag proteins for destruction, acting as both the embryo's internal scaffolding and its primary regulatory system.
From the abstract
Cytoplasmic lattices (CPLs) are filamentous assemblies essential for mammalian embryonic development that regulate organelle organization, spindle assembly, and protein homeostasis. However, their molecular functions remain unclear. Here, we develop a strategy combining cryo-focused ion beam milling and cryo-electron tomography to resolve macromolecular complexes directly in mammalian embryos. Using this approach, we determine the in situ structure of CPLs within mouse embryos at ~4.7 [A] resolu