Figure 6

NSP4 binds to HT-29 cells via a trypsin-sensitive receptor but binding does not require divalent cations. Trypsin-treated HT-29 cells (A) were incubated with 5 μg/ml NSP4 and binding analyzed as described in text. The requirement for divalent cations was examined by inclusion of 10 mM EDTA (B) or EGTA (C) in the binding assay. In each case the dark shaded peak indicates background fluorescence of cells stained with primary and secondary antibody in the absence of NSP4, light shaded peak, cells incubated with NSP4 and the unshaded peak cells incubated with NSP4 plus treatment