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. 2012 Feb 13;109(12):4357–4364. doi: 10.1073/pnas.1200764109

Fig. 5.

Fig. 5.

SapB forms protein–lipid complexes with CD1 lipid antigens. (A) SapB and (B) SapC were incubated with decreasing concentrations of the ganglioside GD1a in sodium citrate (pH 5.0) buffer (lanes 2–5). SapB species (5 μg per sample) were separated by native-PAGE, and total protein was visualized by Coomassie staining. Lanes 6 in A and B show a sample of 84 μM GD1a in the absence of SapB or SapC, respectively. SapB and SapC monomers (open triangles), SapB and SapC dimers (dotted triangles), and SapB dimer–lipid complexes (closed triangles) are indicated at left. (C) SapB and SapC (5 μg) were incubated with αGalCer-biotin (1 μM) for 18 h at pH 5. Samples were neutralized with Tris, pH 9.0, and treated with 1% OsO4 for 10 min and separated by native-PAGE. In-gel detection of αGalCer-biotin was performed by incubating polyacrylamide gel with streptavidin-HRP (Lower). Total protein was visualized by Coomassie stain (Upper). BSA-biotin (0.01 μg) was used as a positive control.