# Making order from disorder in the nucleolus

## TL;DR

This paper explores how disordered protein regions help organize the nucleolus, a key cell structure for ribonucleoprotein assembly.

## Contribution

The study reveals that Nopp140 uses intrinsically disordered regions to mediate interactions critical for nucleolar organization.

## Key findings

- Nopp140's interactions are mediated by intrinsically disordered regions.
- These interactions are essential for the tripartite organization of the nucleolus.
- The findings highlight the role of IDRs in membrane-less organelle assembly.

## Abstract

In this Outlook, Baserga discusses a study in this issue of Genes & Development by Meznad et al. that describes how ribonucleoprotein interactions mediated by protein chaperone Nopp140 drive nucleolar condensate formation and organization. Baserga highlights the central role of intrinsically disordered regions (IDRs) in potentiating the web of protein interactions critical for membrane-less organellar assembly and tripartite nucleolar organization.

The nucleolus and Cajal bodies in the eukaryotic nucleus serve as dynamic hubs for an intricate network of protein–protein and protein–RNA interactions that drive the macromolecular assembly of large and small ribonucleoproteins. However, the mechanisms by which these membrane-less organelles organize their components to fulfill these functions remain largely unknown. In this issue of Genes & Development, Meznad and colleagues (doi:10.1101/gad.353180.125) reveal that the nucleolar and Cajal body protein Nopp140 engages its protein partners through interactions mediated by intrinsically disordered regions. Together, they serve to build the web of interactions required for the tripartite organization of the nucleolus.