Figure 4.

StKRBP1 Specifically Relocalizes Pi04089 to Nuclear Speckles.

(A) Single optical sections of N. benthamiana leaf epidermal cell nuclei transiently co-expressing the GFP-Pi04089 or GFP-SFI3 with RFP-StKRBP1, showing that GFP-Pi04089 is relocated to nuclear speckles, and the nucleolar ring is no longer observed while the localization of GFP-SFI3 remains unaffected. Scale bar represents 10 μm.

(B) Low-magnification images collected with identical imaging parameters and a 10× lens of N. benthamiana leaves, showing that bimolecular fluorescence between YN-Pi04089 and YC-StKRBP1 is more frequently observed than with the YN-SFI3 control and is located in the nuclei of expressing cells. Insets are single optical sections of nuclei, showing that the fluorescence between YN-Pi04089 and YC-StKRBP1 is located in the nuclear speckles. Inset for the YN-SFI3 plus YC-StKRBP1 control combination indicates the level of background non-specific fluorescence observed in a small number of cells.

(C) Graph shows the average number of nuclei observable per field of view using the 10× lens and identical settings for each of the combinations. Significantly more nuclei are observed for YN-Pi04089 and YC-StKRBP1 compared with YN-SFI3 and YC-StKRBP1 (p < 0.001, t test, as indicated by lowercase letters). Error bars are SE, and the graph represents the data from one biological rep (n = 11 fields of view per construct).

(D) Immunoblots indicate that each of the constructs used for bimolecular fluorescence experiments are stable and of the expected size.