Fig. 4. Dynamic relocalization of PP1
by a spatially distinct targeting subunit. Heterokaryons created by the fusion of transiently transfected mammalian cells in the presence of cyclohexamide demonstrate that ECFP-NIPP1 can retarget the nucleolar pool of EYFP-PP1 to nucleoplasmic speckles in both HEK293 (A and B) and HeLa (E and F) cells, whereas the NIPP1(V201K/F203K) mutant cannot (C and D, HEK293; G and H, HeLa). The dashed arrow in Panel E indicates a nucleus within the EYFP-PP1/ECFP-NIPP1 HeLa cell heterokaryon that has a lower level of NIPP1 than its neighbors and shows no significant retargeting of PP1, demonstrating that this is a concentration-dependent effect. Arrows indicate nuclear speckles, whereas arrowheads indicate nucleoli. Scale bars are 10 µM.
