Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1936735 | Biochemical and Biophysical Research Communications | 2007 | 6 Pages |
CD22/Siglec-2 is a B cell membrane-bound lectin that recognizes glycan ligands containing α2,6-linked sialic acid, and negatively regulates signaling through the B cell antigen receptor (BCR). Previous studies demonstrated that synthetic sialosides that bind to CD22 augment BCR signaling by inhibiting CD22-mediated BCR regulation. Here we demonstrate that, after antigen stimulation, CD22 forms a cap together with BCR, and translocates to lipid rafts. Both co-capping of CD22 with BCR and translocation of CD22 to lipid rafts were markedly blocked by a synthetic α2,6-linked sialic acid, Neu5Gcα2-6GalβSE. These results strongly suggest that synthetic glycan ligand excludes CD22 from BCR-containing lipid rafts. Because CD22-mediated signal regulation requires phosphorylation of CD22 by Lyn that localizes in lipid rafts and is activated by BCR, synthetic glycan ligand regulates localization of CD22 crucial for signal regulation.