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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Curr Opin Genet Dev. 2011 Sep 28;21(6):740–746. doi: 10.1016/j.gde.2011.09.007

Figure 2. Concentrating total Cdc42 by GDI-mediated mobilization of GDP-Cdc42.

Figure 2

(A) Inverted images of polarized GFP-Cdc42 in pre-budding yeast cells. Scale bar = 2 µm. Images taken from [28]**. (B) GDI extracts GDP-Cdc42 from the membrane, and rapid cytoplasmic diffusion promotes uniform re-deposition of GDP-Cdc42 all over the membrane. Conversion of GDP-Cdc42 to GTP-Cdc42 within the cluster depletes local GDP-Cdc42, so the rate of GDI-mediated extraction is lower inside the cluster than outside it. Thus, the GDI promotes a net "lux of GDP-Cdc42 from outside to inside the cluster (arrows), resulting in the accumulation of a higher concentration GTP-Cdc42 than the surrounding GDP-Cdc42. (C) Simulation of the dynamic steady state illustrated in B. Color denotes concentration of the indicated species. There is a small depletion of GDP-Cdc42 in the peak that is hard to see with this color bar. See supplement for equations and methods.