Cytoplasmic RNA-Protein Particles Exhibit Non-Gaussian Subdiffusive Behavior

Thomas J. Lampo, Stella Stylianidou, Mikael P. Backlund, Paul A. Wiggins, Andrew J. Spakowitz

Research output: Contribution to journalArticlepeer-review


The cellular cytoplasm is a complex, heterogeneous environment (both spatially and temporally) that exhibits viscoelastic behavior. To further develop our quantitative insight into cellular transport, we analyze data sets of mRNA molecules fluorescently labeled with MS2-GFP tracked in real time in live Escherichia coli and Saccharomyces cerevisiae cells. As shown previously, these RNA-protein particles exhibit subdiffusive behavior that is viscoelastic in its origin. Examining the ensemble of particle displacements reveals a Laplace distribution at all observed timescales rather than the Gaussian distribution predicted by the central limit theorem. This ensemble non-Gaussian behavior is caused by a combination of an exponential distribution in the time-averaged diffusivities and non-Gaussian behavior of individual trajectories. We show that the non-Gaussian behavior is a consequence of significant heterogeneity between trajectories and dynamic heterogeneity along single trajectories. Informed by theory and simulation, our work provides an in-depth analysis of the complex diffusive behavior of RNA-protein particles in live cells.

Original languageEnglish (US)
Pages (from-to)532-542
Number of pages11
JournalBiophysical journal
Issue number3
StatePublished - Feb 7 2017
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics


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