Figure 4

Automated tracing of plasma membrane translocation aequorin responses. A. The βarr2-AEQ probe was used to perform typical screening assays in an automated luminescence plate reader. Panel A shows the recording of the aequorin peaks elicited by Ca²⁺ re-addition to the KRB bathing HeLa cells co-transfected with βarr2-AEQ and βAR. The cells were pre-treated (1 min) or not with isoprenaline (40 μM). The same data are represented in (B) as mean of integral response area (βarr2-AEQ control 11,909 ± 2,351 cps n = 15, βarr2-AEQ + isoprenaline 151,300 ± 24,090 cps n = 11). Panel C illustrates the time course of βarr2-AEQ probe translocation to the plasma membrane of HeLa cells co-transfected with βAR. The light responses were induced by addition (dotted line) or not (solid line) of isoprenaline 40 μM in KRB/Ca²⁺. D. Concentration response curve of cells co-transfected with βarr2-AEQ and βAR, pretreated with various concentrations of isoprenaline. The aequorin light emission responses were triggered by reintroduction of Ca²⁺ as in Figure 3.