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. 2012 Oct 22;3:298. doi: 10.3389/fimmu.2012.00298

Figure 5.

Figure 5

Structure-activity relationship of RvD1, AT-RvD1, and DHA on ALX/FPR2 and DRV1/GPR32 receptors. Activation of ALX/FPR2 and DRV1/GPR32 was determined using the β-arrestin cell system. This system is engineered by stably expressing the target ALX/FPR2 or DRV1/GPR32 tagged with the β-galactosidase Pro-Link peptide. Cells also co-expressed the β-arrestin protein linked to the β-galactosidase EA fragment. In the presence of ligand, activated GPCR interacts with β-arrestin, bringing to proximity the EA and Pro-Link fragments, forming a functional enzyme. β-galactosidase activity is measured by adding the substrate and generating a chemiluminescent signal that is stoichiometrically associated to ligand dependent GPCR activation (see text and Krishnamoorthy et al., 2010 for further details). Dose-response curves show activation of ALX/FPR2 (A) and DRV1/GPR32 (B) receptors by RvD1, AT-RvD1, but not DHA determined using the β-arrestin cell system. Results are mean (±SEM) from n = 4 to 6. RLU, relative luminescence unit.