A Novel Mechanism for Binding of Galactose-terminated Glycans by the C-type Carbohydrate Recognition Domain in Blood Dendritic Cell Antigen 2.
Bottom Line: X-ray crystallography and mutagenesis studies show that mannose is ligated to the conserved Ca(2+) in the primary binding site that is characteristic of C-type carbohydrate recognition domains, and the GlcNAc and galactose residues make additional interactions in a wide, shallow groove adjacent to the primary binding site.As predicted from these studies, BDCA-2 binds to IgG, which bears galactose-terminated glycans that are not commonly found attached to other serum glycoproteins.Thus, BDCA-2 has the potential to serve as a previously unrecognized immunoglobulin Fc receptor.
Affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom.Show MeSH
Mentions: Following expression of the CRD from BDCA-2 in E. coli as inclusion bodies, several protocols for renaturation were investigated, and attempts were made to purify the CRD on high density mannose-Sepharose resin, by analogy to protocols used for mincle and other C-type lectins. When renatured protein was applied to an extended affinity column in a small sample volume, retardation of a band corresponding to the CRD from BDCA-2 was observed (Fig. 2A). Although the protein did not stick tightly to the column and washed through in the presence of Ca2+, the results provide evidence that BDCA-2 has at least weak mannose binding activity.
Affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom.