Figure 3.

Src1- and Src2-EGFP localize to the plasma membrane of growth cones. Live cell fluorescence imaging of Src-EGFP fusion proteins was performed in Aplysia growth cones by acquiring DIC images (A, E, I, M, and Q), dextran images in the Texas Red channel (B, F, J, N, and R), and EGFP images in the FITC channel (C, G, K, O, and S). Overlays of the dextran and EGFP images are shown in (D, H, L, P, and T). (A–D) EGFP and dextran show a volume-dependent distribution in all growth cone domains. The arrow marks a T zone ruffle (D). (E–H) Src1-EGFP and (I–L) Src2-EGFP distribution indicate plasma membrane association. The white arrowhead in K marks the P domain of a second growth cone growing on top of the large growth cone, resulting in an even Src2 signal at higher intensity. Src1 G2A-EGFP (M–P) and Src2 G2A-EGFP (Q–T) exhibit a volume-dependent distribution. The arrows in P and T point toward T zone ruffles that exhibit higher signals than adjacent P domain areas. Absolute signal intensities of these G2A mutants were clearly lower compared with EGFP signals. Bars, 10 μm.