The close correspondence between the measured 3.7 nm length of individual repeats in the neck domains obtained from the crystallographic and forceÀdistance measurements strongly reinforces proposed models for the organization of the extracellular domain with extended neck regions. 17 Hydrodynamic measurements and crystal structures of fragments of the extracellular portions of DC-SIGN and DC-SIGNR generated predictions that the CRDs in these two receptors would be positioned differently, in part due to differences within the final neck repeat adjacent to the CRD that would lead to splaying apart of the CRDs in DC-SIGNR. 17, 19, 32, 33 The forceÀdistance measurements provide experimental evidence that, although these receptors are very similar, they differ in overall length and thus in the disposition of the CRDs.