The adhesion energies per area measured with the 7-repeat and 6-repeat variants are respectively 0.32 ( 0.04 and 0.13 ( 0.03 mJ/m 2 ( Table 2) . When normalized by the protein density on the membranes, the estimated adhesion energies per tetramer are E Adh,7 = 8.0 ( 1.3 kT/molecule and E Adh,6 = 6.9 ( 2.1 kT/ molecule, respectively ( Table 2) . Estimating the adhesion energy per DC-SIGNR molecule for the 5-repeat form is not feasible because of the decreased tetramer stability caused by the truncation associated with the addition of the histidine tag employed in these force measurements. 19 Comparing the estimated, population-averaged adhesion energy per monomer ( Figure 4A ) may provide a better basis for comparison of adhesion by the different DC-SIGNR forms. The calculated energies per monomer for the 7-repeat and 6-repeat forms are 2.0 ( 0.2 and 1.7 ( 0.4 kT/monomer, respectively. These values are statistically similar (p value = 0.7, DF = 12). They are also similar to the adhesion energy per DC-SIGN monomer of 2.0 ( 0.3 kT/monomer (p value = 0.3, DF = 18) after 8 min of contact. 18 However, the calculated adhesion energy per monomer for the 5-repeat DC-SIGNR is 0.2 ( 0.1 kT/ monomer.