Fig. 2. The second RNA-recognition motif is required for targeting hSF2/AF to the granules. GFP-tagged deletion mutants of hSF2/ASF (green) were transiently expressed in HeLa cells, and their distribution relative to HSF1 (red) was analyzed by immunofluorescence in non heat-shocked and heat-shocked cells. DeletiOn Of tHe RS dOmain (HSF2/ASFRS) or the first RNA-recognition motif (hSF2/ASFRRM1) does not affect the speckled distribution of the protein at 37°C, and does not impede the targeting to nuclear stress granules at 42°C. By contrast, deletion of the second RNA-recognition motif (hSF2/ASFRRM2), which doesnot affect the localization of the protein at 37°C, prevents its stress-induced recruitment to the granules. The RRM2 domain alone is however not sufficient for the targeting to the granules. Bar, 5 µm.