Figure 5. Fmi exists in two functional forms.

(A–C) vang^A3 mutant clone overexpressing Fmi, positively labeled by DsRed (blue), recruits Fz but not Vang across cell boundaries. In the neighboring cells, FzGFP (green in [A]; [B]) is recruited to the Fmi overexpression clone border, but Vang (red in [A]; [C]) is excluded. Arrowhead marks a portion of the clone border.

(D) Vang (visualized with anti-Vang antibody) is recruited to vang^A3 mutant clone borders (arrowheads).

(E–G) Negatively marked (red) fmi clones unrescued (E), rescued with FmiYFP (F), or rescued with Fmi^ΔC (G), all stained with anti-Fmi (green) at 28 hrs APF. Note the zigzag pattern of Fmi within the clones.

(E′, F′) fmi clones unrescued (E′) or rescued with FmiYFP (F′), showing phalloidin stained actin at 35 hrs APF.

(H, I, L–N) Simultaneous overexpression of Fz and Fmi in a clone of wildtype cells (H, I) and a clone of vang^A3 cells (L–N) can modify the direction of Fmi-Fmi signal relay. Overexpression clones are marked by loss of FzGFP expression ([H, I, M]; green in [L]) and endogenous Vang expression ([N]; red in [L]; MARCM). Though some clone borders still recruit FzGFP ([H, I, M]; green in [L]), many borders lose FzGFP expression (yellow dots in [H, I]) and recruit Vang instead ([N]; red in [L]). Cell by cell variation likely results from the variable over-expression levels and thus varying ratio of Fmi and Fz known to be achieved using the GAL4 system.

(J–K) Schematics showing recruitment of Fz across cell boundaries by Fmi overexpression (J), and Vang recruitment in cells neighboring a Fmi + Fz co-overexpression clone (K). F-Fmi (blue) and V-Fmi (orange). Blue cells overexpress Fmi or Fmi + Fz and lack Vang.

(O, P) While overexpression of Fmi^ΔC recruits Fz to neighboring cell boundaries (O; blue dots mark wildtype neighbors), simultaneous overexpression of Fmi^ΔC and Fz reverses this recruitment (P; yellow dots mark wildtype neighbors with decreased Fz recruitment), as was seen for wildtype Fmi (H, I, L, M).