FIGURE 5.

The amphipathic C-helix of kalirin is sufficient to localize GFP to the TGN area in AtT-20 cells. Immunostaining of AtT-20 cells transiently transfected with either GFP fused to the C-helix of kalirin (A) or with GFP fused to Kal-C-helix_KKED (B); mutations were introduced to maintain helicity but eliminate the amphipathic nature of the helix. Helical wheel projection diagrams (HeliQuest) for the two peptides are shown to the right. The merged images show GFP in green, TGN38 in red, and Hoechst in blue. Scale bar, 20 μm. The TGN localization score, calculated as described in the legend to Fig. 4, was higher in cells expressing Kal-C-helix-GFP than in cells expressing Kal-C-helix_KKED-GFP (p < 0.001, Student's t test) (C) and was negatively correlated with the GFP expression level (D). Error bars, S.E.