Figure 9. BiP-GFP as a Live Cell Reporter of Changes in the Unfolded Secretory Protein Burden.
(A) Illustration of how interactions of the chaperone BiP with unfolded proteins will change its hydrodynamic radius (Rh) and thus decrease or increase its ability to diffuse D. (B) FRAP of BiP-GFP in untreated and stressed (5 mM DTT 30 min) cells. ROI recovers nearly completely by 8 s for untreated cells, but is still incompletely recovered at 18 s for stressed cells with a large burden of unfolded secretory proteins.