FIGURE 1.

Complementation (BiFC) experiments using various chemokine receptors. HEK293 cells were co-transfected for 48 h with various constructs harboring nonfunctional parts of the YFP variant, Venus. Upon interaction between two receptors, the Venus parts can associate together and regenerate a functional fluorescent signal. a, representation of constructs used in the experiments. b, acquisition of BiFC signals was done in a fusion plate reader (PerkinElmer Life Sciences) bearing filters allowing the measurement of the light that passed by the 535/25-nm bandpass filters (YFP). Results are shown as the relative fluorescence units, and experiments were repeated three times. *, p < 0.05; **, p < 0.01 compared with controls using two-tailed paired Student's t test. c, fluorescence images of bimolecular fluorescence pairs when co-expressed together.