GFP Diffusion coefficient in eukaryotic cytoplasm

Value 27 µm^2/sec
Organism Chinese hamster ovary (CHO)
Reference Elowitz MB, Surette MG, Wolf PE, Stock J, Leibler S. (1997), Photo-activation turns green fluorescent protein red, Curr. Biol, 7 (10) p. 811 right column 3rd paragraphPubMed ID9368766
Primary Source Swaminathan R, Hoang CP, Verkman AS. Photobleaching recovery and anisotropy decay of green fluorescent protein GFP-S65T in solution and cells: cytoplasmic viscosity probed by green fluorescent protein translational and rotational diffusion. Biophys J. 1997 Apr72(4):1900-7.PubMed ID9083693
Method Primary source (abstract):"The green fluorescent protein (GFP) was used as a noninvasive probe to quantify the rheological properties of cell cytoplasm."
Comments "These measurements show that GFP diffusion in the cytoplasm of E. coli strain DH5a is twelve times slower than in water (where D = 87 µm^2/sec) and almost four times slower than the value reported for eukaryotic cytoplasm (D = 27 µm^2/sec in CHO cells) [primary source]. Specifically, from photoactivation experiments, [investigators] obtained an average diffusion constant Dact = 6.7 ±1.6 µm^2/sec, while photobleaching gave [them] Dbleach = 6.0 ±1.0 µm^2/sec (n = 19 cells). The average ratio of Dact to Dbleach on the same cell was 1.1 ±0.1 ( Figure 3, bottom graph). It is possible to photodamage cells significantly by photobleaching GFP with high-intensity illumination. The photoactivation method has the advantage over photobleaching of requiring significantly less energy (a factor of 10 in these experiments). No phototoxicity was observed in [their] experiments (data not shown)." Primary source (abstract) says that relative viscosity of cytoplasm (vs. water) is 3.2. Dividing diffusion coefficient of GFP in water (87µm^2/sec, BNID 100301) by 3.2 gives 27µm^2/sec
Entered by Uri M
ID 101997