FIGURE 6.

The first Ig domain of Beat and Side is required to mediate cell-cell interaction in S2 cells. (A–X) S2 cells were transiently transfected with one of the indicated constructs in separate dishes. After 3 days, cell suspensions were mixed and subjected to cell aggregation assays followed by confocal microscopy. Images in the column to the very right show in addition untransfected cells. (A–D) S2 cells expressing Side-Cherry and Beat-GFP sort themselves out from untransfected cells and form large cell aggregates. (E–H) BeatnewTM-GFP expressing cells interact with Side-Cherry expressing cells. (I–L) Beat_1–322 fails to form cell-cell aggregates with Side-Cherry transfected cells, likely because it is either secreted or not firmly attached to the cell surface. (M–P) BeatΔIg1-GFP does not interact with Side-Cherry-expressing cells. (Q–T) Similarly, SideΔIg1-Cherry is not able to form aggregates with Beat-GFP. (U–X) SideL241H-Cherry also fails to interact with Beat-GFP-expressing cells. Scale bar: 100 μm.