Mazis, G. | Search bioRxiv

bioRxiv2026

Conformational Basis of Functionally Selective Allosteric Modulation of the Angiotensin II type 1 Receptor by Small Molecules

Blockade of signaling through the angiotensin II type 1 receptor (AT1R), a prototypical G protein-coupled receptor (GPCR), by angiotensin receptor blockers (ARBs) is a major therapeutic approach to treating a wide variety of cardiovascular and renal diseases1. Like most GPCRs, the AT1R signals through two transducers, G proteins and {beta}-arrestins2,3. Previous reports have described {beta}-arrestin-biased peptide orthosteric agonists for the AT1R with potential therapeutic advantages over currently available unbiased ARBs4-6. Here we report the DNA- encoded library screening-guided isolation and pharmacological characterization of the first small molecule AT1R allosteric ligands. We use cryo-electron microscopy, double electron- electron resonance spectroscopy, molecular dynamics simulations, and targeted mutagenesis to determine their binding sites, binding modes and conformational mechanisms driving their unique and divergent modulatory effects on G protein and {beta}-arrestin pathways. Our findings uncover new mechanisms for precisely controlling the dynamic behavior of the AT1R with implications for drug development targeting this pathophysiologically important receptor family.

biochemistry↗

bioRxiv2024

LYMTACs: Chimeric Small Molecules Repurpose Lysosomal Membrane Proteins for Target Protein Relocalization and Degradation

Proximity-inducing modalities that co-opt cellular pathways offer new opportunities to regulate oncogenic drivers. Inspired by the success of proximity-based chimeras in both intracellular and extracellular target space, here we describe the development of LYsosome Membrane TArgeting Chimeras (LYMTACs) as a novel small molecule-based platform that functions intracellularly to modulate the membrane proteome. Conceptually, LYMTACs are heterobifunctional small molecules that co-opt short-lived lysosomal membrane proteins (LMPs) as effectors to deliver targets for lysosomal degradation. We demonstrate that a promiscuous kinase inhibitor-based LYMTAC selectively targets membrane proteins for lysosomal degradation via RNF152, a short-lived LMP. To extend these findings, we show that oncogenic, membrane-associated KRASG12D protein can be tethered to RNF152, inducing KRAS relocalization to the lysosomal membrane, inhibiting downstream phospho-ERK signaling, and leading to lysosomal degradation of KRASG12D in a LYMTAC-dependent manner. Notably, potent cell killing could be attributed to the multi-pharmacology displayed by LYMTACs, which differentiates the LYMTAC technology from existing modalities. Thus, LYMTACs represent a proximity-based therapeutic approach that promises to expand the target space for challenging membrane proteins through targeted protein relocalization and degradation.

cancer biology↗