Figure 3.

Photoswitching correction. (A) We performed FRAP on nuclei of live cells expressing H2B-GFP bleaching a small circular spot (diameter 2.0 μm) with different laser intensities (see legend below A and B). (B) After application of our correction procedure for photoswitching, the fast components of all H2B curves were reduced to 0–2% with a mean fast component of 1%. Note that the corrected curves are smooth, since they reflect a fit of the data using the photoswitching model. (C) We estimated the fast component of H2B under each photobleaching condition before and after the correction. The fast components ranged from 8.5–35.8% before the photoswitching correction and were reduced to a mean value of 0.8 ± 0.8% after the photoswitching correction.