Fig. 4. The Cos2 membrane binding domain can tether an exogenous protein to vesicles.

A, S2 cells expressing eGFP-Cos2ΔN or eGFP were fixed, stained with 4,6-diamidino-2-phenylindole (DAPI) (blue) and observed by fluorescence microscopy. The distribution of eGFP-Cos2ΔN is cytoplasmic and punctate similar to full-length Cos2 (see Fig. 2B). However, eGFP is predominantly nuclear with a diffuse cytoplasmic pattern. B, S2 cells were transfected with eGFP-Cos2ΔN, fixed, and stained with α-Rab11 (red) and observed by confocal microscopy. Rab11 is a marker for early/recycling endosomes (73). Plain arrows indicate eGFP-Cos2ΔN signal alone; filled arrows indicate yellow puncta where co-localization of Rab11 and Cos2 signals occurs.