Structural dynamics of kappa opioid receptor interactions with β-arrestin 1.

Han, Jianming; Fine, Eve J; Jiang, Qianru; Zhuang, Yuxuan; Suomivuori, Carl-Mikael; Chen, Zi-Wei; Denn, Elizabeth; Whiddon, Kyle et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Opioid receptors signal through Gi/o protein and β-arrestin pathways that mediate distinct effects of opiate drugs. While opioid binding and G protein activation are well studied, β-arrestin recruitment remains poorly understood. Here, we determine the complex structure of the kappa opioid receptor (KOR) with β-arrestin1 (βarr1) at 2.60 Å resolution using cryogenic electron microscopy. Structural and mass spectrometry analyses reveal multiple phosphorylation sites and a phospholipid-binding site that specifically enhances arrestin recruitment. The KOR-βarr1 complex adopts a core interaction and exhibits notable differences from other GPCR-βarr1 complexes. Comparisons with the structures of KOR-Nb39 and KOR-Gi1 complexes also reveal distinct structural features in the orthosteric binding site and the KOR-transducer interface that affect signaling bias. Using extensive 3D variation analysis and molecular dynamics simulations, we identify a range of conformational dynamics in both the receptor and βarr1, suggesting an allosteric pathway for arrestin's entry and exit.