7XT8 image
Entry Detail
PDB ID:
7XT8
EMDB ID:
Title:
Serotonin 4 (5-HT4) receptor-Gs-Nb35 complex
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2022-05-16
Release Date:
2022-07-27
Method Details:
Experimental Method:
Resolution:
3.10 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Guanine nucleotide-binding protein G(s) subunit alpha isoforms short
Chain IDs:A
Chain Length:394
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1
Chain IDs:B
Chain Length:345
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2
Chain IDs:C (auth: G)
Chain Length:71
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Nanobody35
Chain IDs:D (auth: N)
Chain Length:139
Number of Molecules:1
Biological Source:Lama glama
Polymer Type:polypeptide(L)
Description:Soluble cytochrome b562,5-hydroxytryptamine receptor 4
Chain IDs:E (auth: R)
Chain Length:527
Number of Molecules:1
Biological Source:Homo sapiens
Primary Citation
GPCRs steer G i and G s selectivity via TM5-TM6 switches as revealed by structures of serotonin receptors.
Mol.Cell 82 2681 2695.e6 (2022)
PMID: 35714614 DOI: 10.1016/j.molcel.2022.05.031

Abstact

Serotonin (or 5-hydroxytryptamine, 5-HT) is an important neurotransmitter that activates 12 different G protein-coupled receptors (GPCRs) through selective coupling of Gs, Gi, or Gq proteins. The structural basis for G protein subtype selectivity by these GPCRs remains elusive. Here, we report the structures of the serotonin receptors 5-HT4, 5-HT6, and 5-HT7 with Gs, and 5-HT4 with Gi1. The structures reveal that transmembrane helices TM5 and TM6 alternate lengths as a macro-switch to determine receptor's selectivity for Gs and Gi, respectively. We find that the macro-switch by the TM5-TM6 length is shared by class A GPCR-G protein structures. Furthermore, we discover specific residues within TM5 and TM6 that function as micro-switches to form specific interactions with Gs or Gi. Together, these results present a common mechanism of Gs versus Gi protein coupling selectivity or promiscuity by class A GPCRs and extend the basis of ligand recognition at serotonin receptors.

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