Fig. 4. Targeting of active PP1 to NE-bound AKAP149 is required for B-type lamin assembly in vitro. (A) Nuclei were assembled in a nuclear reconstitution assay containing no peptide (–), 10 µM RVXF or 10 µM RAXF peptide. Where indicated, 1 µM I-2 or 100 nM okadaic acid (OA) were added one hour after initiation of nuclear reformation in the absence of peptide. PP1 distribution and B-type lamin assembly were analyzed by immunofluorescence two hours after initiation of the assembly reaction. Inset, nuclear membrane staining with 10 µg/ml DiOC₆. Bar, 10 µm. (B) Percentages (±s.d.) of nuclei harboring perinuclear B-type lamin and perinuclear PP1 labeling under each condition (n300 nuclei/treatment in duplicate experiments).