Binding of lysoPCh to sEPCR. (A) Delipidated sEPCR was incubated with increasing amounts of 16:0, 18:0, and 18:1 lysoPCh, 760 Da MW PCh, and PAF, and the change in the sEPCR intrinsic fluorescence was registered. A representative experiment is shown for each lipid. The absolute changes in fluorescence on addition of LPC 16:0, LPC 18:0, LPC 18:1, PC, and PAF were 1.22, 1.05, 1.23, 0.31, and 0.4, respectively. (B) SPR analysis of the binding of APC to delipidated sEPCR reconstituted with PCh or lysoPCh. sEPCR or delipidated sEPCR was captured on a CM5 chip through RCR-2 mAb. Binding at equilibrium of 100nM APC to sEPCR and to delipidated sEPCR preincubated or not with PCh or lysoPCh is shown. Data are mean ± SD of 3 independent experiments. Mann-Whitney U test was used for statistical comparisons. Dlip-sEPCR indicates delipidated sEPCR. (C) SPR analysis of the binding of APC to sEPCR reconstituted with lysoPCh. sEPCR was captured on a CM5 chip through RCR-2 mAb. Binding at equilibrium of 100nM APC to sEPCR preincubated or not with different species of lysoPCh is shown. Data are mean ± SD of 3 independent experiments. Mann-Whitney U test was used for statistical comparisons. (D) SPR analysis of the binding of APC to sEPCR reconstituted with PAF. APC-PPACK-b was captured onto an SA chip. Binding at equilibrium of 100nM sEPCR, delipidated sEPCR, PAF-relipidated sEPCR, and sEPCR preincubated with PAF are shown. Data are mean ± SD of 3 independent experiments. Mann-Whitney U test was used for statistical comparisons. Dlip-sEPCR indicates delipidated sEPCR.