Figure 1. Overall structures of binary and ternary complexes of ERGIC-53–CRD.

(A) Schematic representation of Glc₁Man₉GlcNAc₂ showing the nomenclature of oligosaccharide residues and branches. Glucose residue is shown in red. Ribbon models of binary and ternary complexes of ERGIC-53–CRD are shown in (B) and (C), respectively. Ca²⁺-free ERGIC-53–CRD and Ca²⁺/α2-Man₃-bound ERGIC-53–CRD are colored pink and cyan, respectively. MCFD2 is shown in wheat. The bound α2-Man₃ and Ca²⁺ ions are shown as green stick and magenta sphere models, respectively. In the trimannosyl ligand, the two mannose residues giving unambiguous electron densities were drawn. Ca²⁺-binding loops (residues 155–161 and 176–185) are highlighted in orange in (C).