Biomolecular condensates organize cellular contents. Most studies focus on passive phase separation, driven by salt, pH, or temperature. But what if intracellular movement also matters? science.org/doi/10.1126/sc… Here, we explore motility-induced condensation in a cellular context.

In plants, the transcription factors ARF7 & ARF19 control gene expression in response to auxin. But these ARFs can be sequestered into cytoplasmic condensates—shutting down their activity. Why do these condensates form only in the cytoplasm?

We measured ARF concentrations inside the nucleus and cytoplasm of Arabidopsis cells. Surprise: Dilute ARF19 levels were higher in the nucleus, yet condensates formed only in the cytoplasm. That means it’s not just about concentration—it’s about context.

ARF condensates move along actin filaments in the cytoplasm! We found this movement was: fast (~10 µm/s),  directional, and disrupted by actin depolymerization = all signatures of active transport via myosin motors.