Spheres, worms, and packing problems in the nanoscale assembly of ALS-linked protein Matrin-3.

Matrin-3 (MATR3) is an RNA-binding protein that forms higher-order assemblies and pathological inclusions associated with neurodegenerative diseases. In this issue of Molecular Cell, Sprunger et al.1 explore the assembly of MATR3 and find that it forms spherical and worm-like nanoscale assemblies distinct from condensates formed by macrophase separation.