Biology subjects

Koeck, Z.

Publications and source records attributed to Koeck, Z..

2 recordsLinked to original sources

bioRxiv2025

Cryo-EM structure of a cell-free synthesized full-length human β1-adrenergic receptor in complex with Gs

The third intracellular loop (ICL3) of the {beta}1-adrenergic receptor ({beta}1AR) 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 {beta}1AR in complex with Gs or a G protein mimetic nanobody. To address this, we used cell-free cotranslational insertion of full-length human {beta}1AR into nanodiscs and determined its cryo-EM structure in complex with Gs. In this structure, ICL3 extends transmembrane helix 5, resulting in enhanced interactions with Gs and in a slight rotation of the engaged G protein. This repositioning enables new polar interactions between Gs, ICL2 and helix 8, while ICL1 and helix 8 form additional contacts with G{beta}. 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.

biochemistry↗

bioRxiv2023

Cryo-EM structure of cell-free synthesized human histamine H2 receptor coupled to heterotrimeric Gs protein in lipid nanodisc environment

Here we describe the cryo-electron microscopy structure of the human histamine 2 receptor (H2R) in an active conformation with bound histamine and in complex with Gs heterotrimeric protein at an overall resolution of 3.4 [A]. The complex was generated by cotranslational insertion into preformed nanodisc membranes using cell-free synthesis in E. coli lysates. It is the first structure obtained by this detergent-free strategy and the first GPCR/Gs complex structure in lipid environment. Structural comparison with the inactive conformation of H2R and the inactive and Gq-coupled active state of H1R together with structure-guided functional experiments reveal molecular insights into the specificity of ligand binding and G protein coupling for this receptor family. We demonstrate lipid-modulated folding of cell-free synthesized H2R, its agonist-dependent internalization and its interaction with endogenously synthesized H1R and H2R in HEK293 cells by applying a recently developed nanotransfer technique.

molecular biology↗