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. Author manuscript; available in PMC: 2010 Aug 6.
Published in final edited form as: Cytometry A. 2009 Mar;75(3):264–270. doi: 10.1002/cyto.a.20670

Figure 2.

Figure 2

Direct comparison of unlabeled FPR and FPRL1 peptide ligands through a competitive binding assay with the fluorescent WK(FL)YMVm probe. A: This plot shows the direct comparison of the FPR selective formylpeptide ligands (fML, fMLF, fMLFF) with the FPRL1 selective WKYMVm in FPR expressing U937 cells. The high-affinity fMLFF stands out with a 1.0 ± 0.6 nM EC50 while WKYMVm is only 43.8 ± 4.3 nM. The other ligands, fML and fMLF, had EC50 values in the 100 nM range. B: In FPRL1 expressing RBL cells the WKYMVm ligand shows high affinity (EC50 = 1.8 ± 0.3 nM), whereas the formyl peptides are all effectively nonbinding. C: The W-peptides WKRMVm and WKGMVm show no binding in FPR expressing U937 cells. D: Moderate binding of the W-peptides is demonstrated in FPRL1 expressing RBL cells at EC50 values of 704.8 ± 384.1 nM and 175.6 ± 40.6 nM for WKRMVm and WKGMVm, respectively.