Bimolecular fluorescence complementation and immunofluorescence (A, B).

<p>Shown were fluorescence images of CHO cells expressing various receptor constructs, as indicated. The positive results of immunofluorescence using antibody against PAC1 showed that all constructs expressed PAC1 or D-PAC1. Cells transfected with alone Y/N- or Y/C- tagged receptors did not produce YFP fluorescence. YFP fluorescence could be visualized in the cells transfected with the PAC-Y/N +PAC-Y/C supporting homo-dimerization of PAC1. The cells transfected with D-PAC-Y/N +D-PAC-Y/C produced no YFP fluorescence. Absence of fluorescence supported no physical interaction between PAC1 and D-PAC1, while D-PAC-YFP was used as a positive control producing YFP fluorescence. Bar, 5 µm. The statistical analysis of the YFP fluorescence intensity (C) showed that only cells tranfected with PAC-Y/N +PAC-Y/C or D-PAC-YFP (positive control) had significantly higher YFP fluorescence intensity than the negative control (cells without transfection) (*p<0.01 vs. no transfection). Data were presented as means±S.E. of six independent experiments.