Transfected ECSCR and endogenous KDR colocalize at the edge of cultured endothelial cells. Human ECSCR cDNA was generated with a C-terminal V5 tag and overexpressed in HUVECs. (A) Triple label confocal micrograph comparing transfected ECSCR (green) to phalloidin (red) and DAPI (4,6 diamidino-2-phenylindole; blue). Transfected ECSCR is enriched in actin-rich membrane protrusions. Scale represents 40 μm. (B-D) Higher magnification view of a different cell labeled with anti-V5 (top), phalloidin (center), and ARPC2, a component of the Arp2/3 complex (bottom). ECSCR localizes to areas of active membrane protrusion. (E-G) Comparison of ECSCR with KDR. Confocal antitag (panel D and red signal in panel F) and antiendogenous KDR (panel E and green signal in panel F) cytochemistry. The punctate vesicular pattern of KDR overlaps with ECSCR at convex membrane protrusions where KDR approaches the membrane (seen as yellow), but not away from the cell edge. Scale bar represents 10 μm. Results were replicated in 3 independent experiments.