Crystal structure of human dendritic cell inhibitory receptor C-type lectin domain reveals the binding mode with N-glycan.

Human dendritic cell inhibitory receptor (DCIR) is a C-type lectin receptor expressed in classical dendritic cells and accepts several oligosaccharide ligands including N-glycans. Here, we report the crystal structures of human DCIR C-type lectin domains in the absence and presence of a branched N-glycan unit. The domain has a typical C-type lectin fold and two bound calcium ions. In the ligand-bound form, the disaccharide unit (GlcNAcβ1-2Man) acceptably fits the electron density map, indicating that it forms the main epitope. The recognition of the nonterminal N-glycan unit explains the relatively broad specificity of this lectin.