Matthias Weiss: "Protein motion in living cells – anomalous is normal"

Dr. Matthias Weiss
Bioquant Center, German Cancer Research Centre, Heidelberg

Protein motion in living cells – anomalous is normal

Diffusion is the basic means of intracellular transport, e.g. for membrane-bound and solu-ble proteins. However, due to macromolecular crowding and oligomerization processes, the random walk may be obstructed and a change in the diffusion characteristics towards anomalous diffusion (‘subdiffusion’) is anticipated. Using fluorescence correlation spec-troscopy (FCS) in combination with computer simulations, we were able to determine and quantify the subdiffusive motion of transmembrane and soluble proteins. In the latter case, quantifying the anomalous diffusion allows one to determine the viscoelastic proper-ties (i.e. the complex shear modulus) of the intracellular fluids on the nanoscale in vivo. Based on the observation that anomalous diffusion is indeed a fairly common phenome-non, we finally discuss how generic cellular processes (e.g. complex formation) are al-tered in the presence of subdiffusion.