Fig. 5. Domain dependence of NAB formation. (A-D) Targeting of the GFP-jerker peptide construct (B) to nucleoli, as revealed by labeling with nucleolin antibody (C). (E,F) Colocalization of GFP-jerker espin (E) and F-actin labeled with Texas-Red-phalloidin (F) in a NAB. (G,H) Targeting of the GFP-jerker peptide construct to the nucleolus (G) does not cause F-actin accumulation (H). (I,J) The GFP-jerker espin WH2-domain-deletion construct is targeted to nucleoli and to small foci in the nucleoplasm (I), but fails to accumulate F-actin in the nucleus (J). (K,L) Reintroduction of an upstream WH2 domain into GFP-jerker espin WH2-domain-deletion construct results in restoration of NAB-forming activity, causing the colocalization of GFP construct (K) and F-actin (L) in a large NAB. (M,N) The GFP-villin-jerker peptide is targeted to nucleoli (M), but does not cause accumulation of nuclear F-actin (N). (O,P) Introduction of the espin WH2 domain upstream of the villin-jerker peptide construct confers NAB forming activity and causes colocalization of the GFP–WH2-domain–villin-jerker peptide construct (O) with F-actin (P) in fine NABs. Blue, nuclei labeled with DAPI. Bar, 10 µm.