Affinities for C1q.

(A) Representative SPR-derived binding curves for CR1 15–25 variants flowed over a CM5 chip loaded (via amine coupling) with C1q (see also Fig. S4). Upper: sensorgrams recorded for a range of CR1 15–25 concentrations (as in Fig. 3). Lower: plots of response versus [CR1 15–25] used to calculate (see Methods) the K_D values listed in Table 2. CR1 variants that are widespread amongst Caucasoids (KR) or Africans (EG) bind equally to C1q. (B) Data obtained by ELISA showing that C1q (140 ng.mL⁻¹, average of three experiments) bound equally to each of the four variants of CR1 15–25 (adhered to the micro-titer plate). In these experiments, sCR1 was used as a positive control. Error bars represent standard errors of the mean.