Comparison of the D C or D eq values for the 7-repeat DC-SIGNR with an exactly equivalent construct for the extracellular domain of DC-SIGN 18 reveals that the average difference of 1.3 nm is larger for DC-SIGN than for DC-SIGNR (p < 0.05, DF = 13; Table 1 ). In pairwise comparisons, a p value less than 0.05 signifies a statistically significant difference at the 95% confidence level. As noted in Figure 1 , differences in the sequence of the neck repeat adjacent to the CRD in DC-SIGNR are postulated to result in the splaying apart of this repeat and the CRDs compared to DC-SIGN ( Figure 1B) , which would make the bound thickness of DC-SIGN slightly longer than DC-SIGNR. 17 Thus, the forceÀdistance measurements provide experimental evidence to support this model of the differences in the arrangement of the distal portion of the DC-SIGN and DC-SIGNR extracellular domains ( Figure 1B) .