Fig. 5. Sun1 contains multiple, independent nuclear targeting signals. (A) Schematic representation of Sun1 GFP fusion constructs. Domain labelling is as in Fig. 2A. (B-I) Subcellular localisation of GFP Sun1 fusion proteins in COS7 cells observed by direct fluorescence confocal microscopy. Arrows indicate NE localisation whereas arrowheads indicate ER localisation. DAPI was used to counter-stain the nuclei. (J) Histogram representing a statistical evaluation (percentage of transfected cells) of the localisation profiles of the various SUN1-GFP fusions to the ER and the NE. Bars, 10 µm.