8S2T

Cryo-EM structure of cell-free synthesized Human beta-1 adrenergic receptor cotranslationally inserted into a lipidic nanodiscs

Summary for 8S2T

• Entry DOI: 10.2210/pdb8s2t/pdb
• EMDB information: 19683
• Descriptor: Isoform Gnas-2 of Guanine nucleotide-binding protein G(s) subunit alpha isoforms short, Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1, Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2, ... (6 entities in total)
• Functional Keywords: signal transduction, gpcr, co-translational nanodisc insertion, g-protein, membrane protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 5
• Total formula weight: 155673.97

Authors

Merino, F.,Koeck, Z.,Ermel, U.,Dahlhaus, P.,Doetsch, V.,Kubicek, J.,Frangakis, A.S.,Hilger, D.,Bernhard, F. (deposition date: 2024-02-19, release date: 2025-05-21, Last modification date: 2025-09-17)

Primary citation

Merino, F.,Kock, Z.,Ermel, U.,Dahlhaus, P.,Grimm, A.,Seybert, A.,Kubicek, J.,Frangakis, A.S.,Dotsch, V.,Hilger, D.,Bernhard, F.
Cryo-EM structure of a cell-free synthesized full-length human beta 1-adrenergic receptor in complex with G s.
Structure, 2025

PubMed Abstract: The third intracellular loop (ICL3) of the β1-adrenergic receptor (β1AR) plays a critical role in regulating G protein coupling, yet the structural basis has remained unclear due to truncations of ICL3 in all available structures of the β1AR in complex with G or a G protein mimetic nanobody. To address this, we used cell-free cotranslational insertion of full-length human β1AR into nanodiscs and determined its cryo-electron microscopy (cryo-EM) structure in complex with G. In this structure, ICL3 extends transmembrane helix 5, resulting in enhanced interactions with Gα and in a slight rotation of the engaged G protein. This repositioning enables new polar interactions between Gα, ICL2 and helix 8, while ICL1 and helix 8 form additional contacts with Gβ. These structural insights, supported by mutational analysis, demonstrate that ICL3 enhances G protein activation and downstream cAMP signaling by promoting more extensive interactions between the receptor and the heterotrimeric G protein.

PubMed: 40858117
DOI: 10.1016/j.str.2025.07.020

Experimental method

ELECTRON MICROSCOPY (3.3 Å)