Extended Data Fig. 9: Receptor transmembrane dimer interface of various CaSR-G-protein complexes.
From: Promiscuous G-protein activation by the calcium-sensing receptor
a, Structural elements at the receptor TMD dimer interface of CaSR-Gi3 (blue and cyan), CaSR-miniGisq (green) and CaSR-miniGis (yellow) complexes in nanodiscs, as well as those of CaSR-miniGisq (blue) and CaSR-miniGi1 (violet) complexes in detergent. b, Specific TMD dimer interactions between CaSRfree (blue) and CaSRG (cyan) within each of the CaSR-G-protein complexes shown in (a). The TMD dimer interface is divided into three sections (I-III) based on the contacts involving TM6 (I), TM7 (II) and ECL3 (III) of CaSRfree. In the cases of CaSR-miniGis in nanodiscs and CaSR-miniGi1 in detergent, TM1 of CaSRfree contributes to dimer interactions in section II. An additional interaction between ECL2 of both subunits is found in the CaSR-miniGis complex and included as part of section III. F8216.53(G) is part of the dimer interface, while F8216.53(free) (yellow) is directed toward the transmembrane core. Hydrogen bonds are depicted by dashed lines. c, d, Functional analysis of mutations at the receptor TMD dimer interface and phospholipid-binding site. Ca2+ potency (EC50) and maximal response (Emax) of wild-type and mutant receptors are compared for Gq, Gqi9 and Gqs5 (c) as well as Gq and Gi3 (d) using IP1 accumulation and BRET-based G-protein activation assay, respectively. Most of the mutants showed reduced G-protein activation when compared to the wild-type receptor. Bar segments represent averages ± s.e.m, with the number of independent experiments (n) indicated. One-way analysis of variance (ANOVA) with Dunnett’s multiple comparison test was used to calculate statistical differences in EC50 and Emax between wild-type and mutant receptors. ND stands for not determined due to an incomplete response curve within the dose concentration range tested. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant. Cell surface expression levels of wild-type and mutant CaSR are described in in the Methods.
