Fig. 4: Soluble Dpep(20-42)DM and Mpep(32-61)DM peptides suppress DM heterodimerization.
a Effect of the addition of 1 µM soluble peptides with the same amino-acid sequences as various parts of the N-terminal domains of DOR and MOR (DpepDM and MpepDM, respectively) on the DM colocalization index. In the box plots, horizontal bars, boxes, and whiskers indicate mean values, interquartile ranges (25–75%), and 10-90% ranges, respectively. b With an increase of the Dpep(20-42)DM concentration, the DM colocalization index decreased. The gray keys at 0 µM Dpep(20-42)DM represent the data points obtained by using rotated overlays. The colocalization index reduces to about the middle value between no addition and the addition of 1 or 10 µM of the Dpep(20-42)DM (saturating conditions) at a Dpep(20-42)DM concentration of 0.1 µM (these are normal 3D concentrations because the peptide is very soluble). Therefore, we conclude that KD for Dpep(20-42)DM binding to MOR is on the order of 0.1 µM. In the box plots, horizontal bars, crosses, boxes, and whiskers indicate median values, mean values, interquartile ranges (25–75%), and 10–90% ranges, respectively. c Dpep(20-42)DM reduces the τ2 of DM colocalization (blue). Histograms for the control (no addition) and rotated overlays of WT DOR-MOR images are the same as those shown in Fig. 1d. In the box plots (a, b), * and ns represent significant (p < 0.05) and non-significant (p ≥ 0.05) differences, respectively (Tukey’s multiple comparison test). The data set used for multiple comparison is indicated by the group of lines in each figure. All of the statistical parameters and analysis results including sample size n and p values are provided in Supplementary Data 2. Source data are provided as a Source Data file.
