the ci-mpr and cd-mpr are able to bind to this wide range of n-glycan structures by having a different binding site architecture. the mprs also bind to the phosphate group in a slightly different manner. domain 3 of the ci-mpr uses ser-386 and an ordered water molecule to bind to the phosphate moiety. on the other hand, the cd-mpr uses residues asp-103, asn-104 and his-105 to form favourable hydrogen bonds to the phosphate group. the cd-mpr also contains a divalent cation mn which forms favourable hydrogen bonds with the phosphate moiety.