Elucidating the molecular logic of a metabotropic glutamate receptor heterodimer.

Metabotropic glutamate (mGlu) receptor protomers can heterodimerize, leading to different pharmacology compared to their homodimeric counterparts. Here, we use complemented donor-acceptor resonance energy transfer (CODA-RET) technology that distinguishes signaling from defined mGlu heterodimers or homodimers, together with targeted mutagenesis of receptor protomers and computational docking, to elucidate the mechanism of activation and differential pharmacology in mGlu heteromers. We demonstrate that positive allosteric modulators (PAMs) that bind an upper allosteric pocket in the mGlu transmembrane domain are active at both mGlu homomers and mGlu heteromers, while those that bind a lower allosteric pocket within the same domain are efficacious in homomers but not heteromers.

Promiscuous G-protein activation by the calcium-sensing receptor.

The human calcium-sensing receptor (CaSR) detects fluctuations in the extracellular Ca concentration and maintains Ca homeostasis. It also mediates diverse cellular processes not associated with Ca balance. The functional pleiotropy of CaSR arises in part from its ability to signal through several G-protein subtypes.

Molecular Design of SERTlight: A Fluorescent Serotonin Probe for Neuronal Labeling in the Brain.

The serotonergic transmitter system plays fundamental roles in the nervous system in neurotransmission, synaptic plasticity, pathological processes, and therapeutic effects of antidepressants and psychedelics, as well as in the gastrointestinal and circulatory systems. We introduce a novel small molecule fluorescent agent, termed , that specifically labels serotonergic neuronal cell bodies, dendrites, and axonal projections as a serotonin transporter (SERT) fluorescent substrate. SERTlight was developed by an iterative molecular design process, based on an aminoethyl-quinolone system, to integrate structural elements that impart SERT substrate activity, sufficient fluorescent brightness, and a broad absence of pharmacological activity, including at serotonin (5-hydroxytryptamine, 5HT) receptors, other G protein-coupled receptors (GPCRs), ion channels, and monoamine transporters.

Methods for automating the analysis of live-cell single-molecule FRET data.

Single-molecule FRET (smFRET) is a powerful imaging platform capable of revealing dynamic changes in the conformation and proximity of biological molecules. The expansion of smFRET imaging into living cells creates both numerous new research opportunities and new challenges. Automating dataset curation processes is critical to providing consistent, repeatable analysis in an efficient manner, freeing experimentalists to advance the technical boundaries and throughput of what is possible in imaging living cells.

Free fatty acid receptor 1 stimulates cAMP production and gut hormone secretion through Gq-mediated activation of adenylate cyclase 2.

Objective: Free fatty acid receptor 1 (FFAR1) is highly expressed in enteroendocrine cells of the small intestine and pancreatic beta cells, where FFAR1 agonists function as GLP-1 and insulin secretagogues, respectively. Most efficacious are so-called second-generation synthetic agonists such as AM5262, which, in contrast to endogenous long-chain fatty acids are able to signal through both IP/Ca and cAMP pathways. Whereas IP signaling is to be expected for the mainly Gq-coupled FFAR1, the mechanism behind FFAR1-induced cAMP accumulation remains unclear, although originally proposed to be Gs mediated.