Biology subjects

Dates, A. N.

Publications and source records attributed to Dates, A. N..

5 recordsLinked to original sources

bioRxiv2025

β-arrestin recruitment facilitates a direct association with G proteins

G protein-coupled receptors (GPCRs) are targets for almost a third of all FDA-approved drugs. GPCRs are known to signal through both heterotrimeric G proteins and {beta}-arrestins. Traditionally these pathways were viewed as largely separable, with G proteins primarily initiating downstream signaling while {beta}-arrestins modulate receptor trafficking and desensitization in addition to regulating their own signaling events. Recent studies suggest an integrated role of G proteins and {beta}-arrestins in GPCR signaling, however the cellular and biochemical requirements for G protein: {beta}-arrestin interactions remain unclear. Here we show that G proteins and {beta}-arrestins can directly interact. Through utilization of {beta}-arrestin-biased receptors and artificially enforced {beta}-arrestin relocalization, we demonstrate that recruitment of {beta}-arrestin to the plasma membrane is sufficient to interact with the G protein Gi. Using purified proteins, we show that Gi directly interacts with {beta}-arrestin. In addition, we find that Gi family members differ in their degree of association with {beta}-arrestin, and that a large degree of this selectivity resides within the alpha helical domain of Gi. These findings delineate the cellular and biochemical conditions that drive direct interactions between G proteins and {beta}-arrestins and illuminate the molecular basis for how they work together to effect GPCR signaling.

biochemistry↗

bioRxiv2022

A Spatiotemporal Notch Interaction Map from Membrane to Nucleus

Notch signaling relies on ligand-induced proteolysis to liberate a nuclear effector that drives cell fate decisions. The location and timing of individual steps required for proteolysis and movement of Notch from membrane to nucleus, however, remain unclear. Here, we use proximity labeling with quantitative multiplexed mass spectrometry to monitor the microenvironment of endogenous Notch2 after ligand stimulation in the presence of a gamma secretase inhibitor and then as a function of time after inhibitor removal. Our studies show that gamma secretase cleavage of Notch2 occurs in an intracellular compartment and that formation of nuclear complexes and recruitment of chromatin-modifying enzymes occurs within 45 minutes of inhibitor washout. This work provides a spatiotemporal map of unprecedented detail tracking the itinerary of Notch from membrane to nucleus after activation and identifies molecular events in signal transmission that are potential targets for modulating Notch signaling activity.

molecular biology↗

bioRxiv2022

Tethered agonist activated ADGRF1 structure reveals molecular preference for Gq signaling

Adhesion G-Protein Coupled Receptors (aGPCRs) have evolved an activation mechanism to translate extracellular force into liberation of a tethered agonist (TA) to modulate cell signalling. We report here that ADGRF1 is the first class B GPCR shown to signal through all major G-protein classes and identify the structural basis for its Gq preference by cryo-EM. Our structure shows that Gq over Gs preference in ADGRF1 derives from tighter packing at the conserved F569 of the TA, altering contacts between TM helix I and VII, with a concurrent rearrangement of TM helices VII and VIII at the site of G recruitment. Gs signalling is also more sensitive to mutation of TA or binding site residues than Gq. Our work advances the understanding of aGPCR TA activation in molecular detail, identifying structural features that potentially explain preferential signal modulation.

biochemistry↗

bioRxiv2022

A Fusion Protein Platform for Analyzing Tethered Agonism in the Adhesion Family of G Protein-Coupled Receptors

Adhesion G Protein-Coupled Receptor (aGPCR) signaling influences development and homeostasis in a wide range of tissues. In the current model for aGPCR signaling, ligand binding liberates or unmasks a highly conserved tethered agonist (TA) that acts as an intramolecular ligand to stimulate G protein coupling. However, a systematic, comprehensive examination of signaling has not been performed for all aGPCR family members. Here, we report a platform for profiling TA-dependent activities of aGPCRs in several different assays and apply it to all 33 human family members. Activity profiling identified a heterogeneity of responses among these aGPCRs, with only [~]50% showing robust, TA-dependent signals. AlphaFold2 predictions assessing TA engagement in the predicted intramolecular binding pocket aligned with the TA-dependence of the cellular responses. The signaling information in this dataset is a comprehensive resource relevant for the investigation of all human aGPCRs and for targeting aGPCRs therapeutically.

biochemistry↗

bioRxiv2019

The structure of the yeast Ctf3 complex

Kinetochores are the chromosomal attachment points for spindle microtubules. They are also signaling hubs that control major cell cycle transitions and coordinate chromosome folding. Most well-studied eukaryotes rely on a conserved set of factors, which are divided among two loosely-defined groups, for these functions. Outer kinetochore proteins contact microtubules or regulate this contact directly. Inner kinetochore proteins designate the kinetochore assembly site by recognizing a specialized nucleosome containing the H3 variant Cse4/CENP-A. We previously determined the structure, resolved by cryo-electron microscopy (cryo-EM), of the yeast Ctf19 complex (Ctf19c, homologous to the vertebrate CCAN), providing a high-resolution view of inner kinetochore architecture. We now extend these observations by reporting a near-atomic model of the Ctf3 complex, the outermost Ctf19c sub-assembly seen in our original cryo-EM density. The model is sufficiently well-determined by the new data to enable molecular interpretation of Ctf3 recruitment and function.

cell biology↗