Equilibrium binding studies with recombinant human chemoattractant cytokines Rantes and monocyte chemoattractant protein 1 (MCP-1) on monocytic THP-1 cells have allowed the functional identification of two distinct receptors for C-C chemokines. One is a novel oligospecific receptor with high affinity for Rantes (50% maximal inhibitory concentration [IC50], 0.68 nM) and low affinity (IC50, 35 nM) for MCP-1, while the other is the previously described specific receptor for MCP-1 (IC50, 0.5 nM). Receptor affinity for Rantes is enhanced on preparation of isolated membranes with a 12-fold decrease in receptor Kd. The basis of this enhancement is not understood. The Rantes receptor appears to be G protein linked, as binding activity is abolished by guanosine 5'-O-(3-thiotriphosphate) (IC50, 7.3 nM). In contrast to the consequences of MCP-1 binding, we were unable to demonstrate ligand-dependent calcium fluxes on binding of Rantes to human monocytes or THP-1 cells. The binding of Rantes and MCP-1 to mononuclear cells from dog, rabbit, and rat were tested. While high affinity binding could be demonstrated in dog and rabbit, differences in ligand-induced Ca2+ fluxes could be shown between species. This suggests that receptor-ligand interactions and receptor coupling is best examined with autologous receptors and cytokine.
Characterization and species distribution of high affinity GTP-coupled receptors for human rantes and monocyte chemoattractant protein 1.
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G Van Riper, S Siciliano, P A Fischer, R Meurer, M S Springer, H Rosen; Characterization and species distribution of high affinity GTP-coupled receptors for human rantes and monocyte chemoattractant protein 1.. J Exp Med 1 March 1993; 177 (3): 851–856. doi: https://doi.org/10.1084/jem.177.3.851
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