Transient droplets organize biochemical reactions inside cells

Called condensates, the droplets pull together proteins and RNA when and where they’re needed. Now, they’re on pharma’s radar.

Clifford P. Brangwynne smashed the single-celled embryo between a microscope slide and a thin glass cover slip. Then he peered into the microscope to get a look at the cell, taken from a worm commonly studied in the lab, Caenorhabditis elegans. What he expected to see were small, solid balls, composed of RNA and protein, dotting the cell. But instead, what he saw looked more like the world’s smallest lava lamp.

Rather than drifting throughout the cell’s liquid innards like wooden balls bobbing around in a tank of water, over and over the globs appeared, merged, and separated before disappearing. Brangwynne, then a postdoctoral scholar in Anthony Hyman’s lab at Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), realized: this isn’t something that solids do. The so-called P granules, which scientists had assumed were solids, were actually behaving like liquids…