Figure 6.

The effect of DLL4 lateral mobility, as characterized by diffusion coefficient (D), and density on Notch activation levels. (A) For membrane surfaces with <1500 DLL4-mCherry-biotin molecules per μm², D was varied from ∼0 to 0.6 μm²/s. Notch activation sharply increased as D approached 0. Error bars indicate the standard deviation in reporter intensity as measured from 1000 cells (or more) 48 h after plating. The average D for each surface was determined using a previously published FRAP assay (18). (B) When the D and density were both varied, high levels of Notch activation (normalized reporter intensities >5, red marker) were observed when D neared 0 and when ligand density was increased. To see this figure in color, go online.