Figure 3.

The five-TM chemokine receptor-mediated cellular responses. HEK293 cells transiently (A, B, and D) or stably (C) expressing the wild-type or mutant chemokine receptors were treated with indicated amounts (A and B), 1 nM (C), or 10 nM (D) of chemokines. The chemokine-stimulated G protein activation (A), adenylyl cyclase inhibition (B), cell migration (C), and Ca²⁺ influx (D) were measured. The EC₅₀ values of the chemokine-induced GTPγS binding were estimated: wCCR5, 0.15 nM; mCCR5, 0.18 nM; wCXCR4, 2.6 nM; and mCXCR4, 4.6 nM. The basal GTPγS binding values were in the range of 1.11 ± 0.04 nmol/mg protein. The EC₅₀ values for cyclase inactivation were 30 pM for wCCR5, 22 pM for mCCR5, 200 pM for wCXCR4, and 550 pM for mCXCR4. The untreated forskolin-stimulated cAMP levels were in the range of 129 ± 11 pmol/mg protein. The migration number of the untreated cells was 12.6 ± 0.3. All data are means ± SE of three independent experiments performed in duplicate.