Weaver, M. G. | bioRxiv Science

bioRxiv2026

GluDs are ionotropic dopamine receptors tuned by G-proteins

Dopamine is a neurotransmitter essential for cognition, and its dysregulation is associated with neurological diseases1,2. Historically, dopamine has been understood to signal exclusively through metabotropic receptors3. Delta-type ionotropic glutamate receptors (GluDs), which have recently been established as ligand-gated ion channels4,5, are fundamental for synaptic maintenance, are implicated in neurological disorders, and co-localize with dopaminergic machinery. Here, we report that dopamine is a direct agonist of GluDs, eliciting ionotropic activity, as visualized by cryo-electron microscopy (cryo-EM), bilayer recordings, mutagenesis, and patch clamp recordings. Dopamine binds to the GluD ligand binding domain, inducing clamshell closure and channel activation through a distinct molecular interface. GluD channel activity is tightly regulated by G-proteins, which act as molecular switches to tune GluD activity: free G{beta}{gamma} inhibits ligand-gating, while G or inactive G-protein heterotrimers enable dopamine-induced GluD currents. This tuning of GluD activity by G-proteins is uncoupled in a point mutation associated with neurodegeneration. These findings expand mechanisms of neuronal dopaminergic signaling, uncover how G-proteins tune GluD channel activity, and provide a framework for targeting GluDs in neurological diseases.

biophysics↗

bioRxiv2026

Molecular basis for ligand-gating of the human GluD1 receptor

The delta-type ionotropic glutamate receptors (iGluRs) GluD1 and GluD2 are ligand-gated ion channels that are fundamental for regulating both excitatory and inhibitory synapses. Rising evidence points to the role of GluD1 in the development of neurological diseases. However, the ultrastructure of human GluD1 (hGluD1) and the molecular basis for its ligand-gating remain unclear. Here, we define the structure of hGluD1 and resolve its ligand-gating mechanism using cryo-electron microscopy (cryoEM) and single channel bilayer recording. While hGluD1 exhibits a non-swapped architecture, it contains conserved iGluR moieties that enable ligand-gating, such as a ligand-binding domain (LBD) tethered to a transmembrane ion channel. Binding of the neurotransmitter {gamma}-aminobutyric acid (GABA) or D-serine to the LBD enables cation influx through the hGluD1 ion channel. Our findings delineate the molecular architecture and function of hGluD1, provide foundations for understanding patient mutations in hGluD1, and will invigorate therapeutic development against hGluD1.

biophysics↗