Fig. 2: Interaction between EL3 domains of DOR and KOR is involved in DK heterodimerization, and DOR’s TM1 and TM4 are also involved.
a The N- and C-terminal domains of DOR and KOR are not involved in DK heterodimerization. DK colocalization indexes of N/C-terminal deletion mutants of DOR and full-length KOR (top) and N/C-terminal deletion mutants of KOR and full-length DOR (bottom). b Summary of the names and exact amino-acid ranges of the OR domains and TM1-based peptides employed in this work. c DOR’s EL3, TM1, and TM4, but not EL2 and N-term, are involved in DK heterodimerization. d Both EL3 domains of DOR and KOR are involved in DK heterodimerization. Soluble peptides (1 µM) with the aa sequences of the EL3 domains (EL3-domain peptides) of DOR and KOR, but not that of MOR, block DK heterodimerization. e DOR’s TM1 and TM4 bind to KOR. Colocalization indexes show that the affinities to WT-KOR are greater in the order of WT-DOR > DOR’s TM1 > DOR’s TM4. Because the TM4 orientation in the PM is from the PM cytoplasmic surface toward outer surface, to maintain this orientation, the N-terminus of TM4 was linked to the C-terminus of TMLDLR, which is oriented in the opposite way and does not interact with ORs. In the box plots (a, c–e), horizontal bars, boxes, and whiskers indicate mean values, interquartile ranges (25–75%), and 10-90% ranges, respectively. * 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, and different sets are indicated by different colors. 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.
