CTB binds to Le<sup>X</sup> linked to proteins but not ceramide.

<p><b>(A)</b> GM1- or Le<sup>X</sup>-os (oligosaccharide) linked to ceramide and immobilized to wells were detected with <sup>125</sup>I labeled CTB. Relative binding is displayed as counts per minute (CPM). <b>(B-C)</b> ELISA with titrated amounts of os-linked to HSA, immobilized to wells and detected with <b>(B)</b> CTB-HRP and <b>(C)</b> G33D-HRP. Graph shows absorbance values from three independent experiments. <b>(D)</b> ELISA with os-linked to HSA, immobilized in wells and then blocked with indicated concentrations of anti-Le<sup>X</sup> antibody HI98 or isotype control (IgM), and detected with CTB-HRP. Graph shows absorbance values from one representative out of two independent experiments. <b>(E)</b> ELISA with os-linked to HSA, immobilized in wells and detected with CTB-HRP in the presence of increasing blocking concentrations of tri-Le<sup>X</sup>-os and GM1-os. Graphs show absorbance values from one representative out of two independent experiments.</p>