Precision Aptamers Against a Native GPCR through Ligand-Guided Selection

G protein-coupled receptors (GPCRs) constitute the largest and most diverse class of membrane receptors encoded in the human genome. They detect a wide range of chemical and physical stimuli and transduce these signals into intracellular responses through highly regulated pathways. Reflecting their central role in physiology, GPCRs are among the most prominent targets in drug discovery. However, identifying ligands that recognize GPCRs in their native conformational and membrane context remains a significant challenge. Here, we report an expanded aptamer discovery platform based on ligand-guided selection (LIGS) to isolate aptamers against GPCRs in their native cellular state. Using the β₂-adrenergic receptor (β₂AR) as a model system and employing agonists and antagonists as competing ligands, we identified three aptamers with high specificity for β₂AR. These aptamers exhibit selective binding to cell-surface β₂AR, showing higher apparent affinity towards cell-membrane bound β₂AR than toward the purified receptor, which is consistent with recognition of native receptor context. Beyond target recognition, we show that the selected aptamers induce rapid internalization, indicating functional engagement. Together, these findings establish ligand-guided selection as a generalizable strategy for the discovery of conformationally sensitive aptamers targeting GPCRs in their native membrane environments.