Veprintsev, D. J. | bioRxiv Science

bioRxiv2023

Molecular recognition of an aversive odorant by the murine trace amine-associated receptor TAAR7f

There are two main families of G protein-coupled receptors that detect odours in humans, the odorant receptors (ORs) and the trace amine-associated receptors (TAARs). Their amino acid sequences are distinct, with the TAARs being most similar to the aminergic receptors such as those activated by adrenaline, serotonin and histamine. To elucidate the structural determinants of ligand recognition by TAARs, we have determined the cryo-EM structure of a murine receptor, mTAAR7f, coupled to the heterotrimeric G protein Gs and bound to the odorant N,N-dimethylcyclohexylamine (DMCH) to an overall resolution of 2.9 [A]. DMCH is bound in a hydrophobic orthosteric binding site primarily through van der Waals interactions and a strong charge-charge interaction between the tertiary amine of the ligand and an aspartic acid residue. This site is distinct and non-overlapping with the binding site for the odorant propionate in the odorant receptor OR51E2. The structure, in combination with mutagenesis data and molecular dynamics simulations suggests that the activation of the receptor follows a similar pathway to that of the {beta}-adrenoceptors, with the significant difference that DMCH interacts directly with one of the main activation microswitch residues.

molecular biology↗

bioRxiv2021

Individual cells traffic the Vasopressin 2 Receptor to their cell surface with different success

G protein coupled receptors (GPCRs) translate the actions of hormones into intracellular signalling events. Mutations in GPCRs can prevent their correct expression and trafficking to the cell surface and cause disease. We use single cell measurements in HEK293 cells to show that the balance between endoplasmic reticulum (ER) and cell surface localisation of the Vasopressin 2 receptor (V2R) varies significantly from cell to cell. We find that mutations in the V2R affect the proportion of cells able to send this GPCR to the cell surface but do not prevent all cells in the population from correctly trafficking the mutant receptors. These findings reveal that the ability of cells to correctly traffic V2R to the cell surface depends not only on the expressed V2R mutant but also on the individual cell environment. Significance statementMissense mutations in the Vasopressin 2 Receptor (V2R) cause Nephrogenic Diabetes Insipidus. Some of these mutations prevent correct expression and trafficking of V2R to the cell surface resulting in a loss-of-function. We show -using single cell measurements-that the balance between endoplasmic reticulum and cell surface localisation of the V2R varies significantly from cell to cell, independent from its expression level. Mutations affect the proportion of cells able to send V2R to the cell surface but do not prevent all cells in the population from correctly trafficking the mutant receptors. Hence, the ability of cells to correctly traffic V2R to the cell surface depends not only on expressed V2R mutant but also on the cell environment.

molecular biology↗