Targeting G protein-coupled receptor signaling at the G protein level with a selective nanobody inhibitor

Nat Commun. 2018 May 18;9(1):1996. doi: 10.1038/s41467-018-04432-0.

Abstract

G protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by mediating a GDP to GTP exchange in the Gα subunit. This leads to dissociation of the heterotrimer into Gα-GTP and Gβγ dimer. The Gα-GTP and Gβγ dimer each regulate a variety of downstream pathways to control various aspects of human physiology. Dysregulated Gβγ-signaling is a central element of various neurological and cancer-related anomalies. However, Gβγ also serves as a negative regulator of Gα that is essential for G protein inactivation, and thus has the potential for numerous side effects when targeted therapeutically. Here we report a llama-derived nanobody (Nb5) that binds tightly to the Gβγ dimer. Nb5 responds to all combinations of β-subtypes and γ-subtypes and competes with other Gβγ-regulatory proteins for a common binding site on the Gβγ dimer. Despite its inhibitory effect on Gβγ-mediated signaling, Nb5 has no effect on Gαq-mediated and Gαs-mediated signaling events in living cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Dimerization
  • GTP-Binding Protein alpha Subunits / chemistry
  • GTP-Binding Protein alpha Subunits / genetics
  • GTP-Binding Protein alpha Subunits / metabolism*
  • GTP-Binding Protein beta Subunits / chemistry
  • GTP-Binding Protein beta Subunits / genetics
  • GTP-Binding Protein beta Subunits / metabolism*
  • GTP-Binding Protein gamma Subunits / chemistry
  • GTP-Binding Protein gamma Subunits / genetics
  • GTP-Binding Protein gamma Subunits / metabolism*
  • Guanosine Triphosphate / metabolism
  • Humans
  • Protein Binding
  • Signal Transduction
  • Single-Domain Antibodies / chemistry
  • Single-Domain Antibodies / metabolism*

Substances

  • GTP-Binding Protein alpha Subunits
  • GTP-Binding Protein beta Subunits
  • GTP-Binding Protein gamma Subunits
  • Single-Domain Antibodies
  • Guanosine Triphosphate