Association of heterotrimeric G(i) with the insulin-like growth factor-I receptor. Release of G(betagamma) subunits upon receptor activation.

The insulin-like growth factor-I receptor (IGF-IR) is a key regulator of cell proliferation and survival. Activation of the IGF-IR induces tyrosine autophosphorylation and the binding of a series of adaptor molecules, thereby leading to the activation of MAPK. It has been demonstrated that pertussis toxin, which inactivates the G(i) class ...
of GTP-binding proteins, inhibits IGF-I-mediated activation of MAPK, and a specific role for G(betagamma) subunits in IGF-I signaling was shown. In the present study, we have investigated the role of heterotrimeric G(i) in IGF-IR signaling in neuronal cells. Pertussis toxin inhibited IGF-I-induced activation of MAPK in rat cerebellar granule neurons and NG-108 neuronal cells. G(alphai) and G(beta) subunits were associated with IGF-IR immunoprecipitates. Similarly, in IGF-IR-null mouse embryo fibroblasts transfected with the human IGF-IR, G(i) was complexed with the IGF-IR. G(alphas) was not associated with the IGF-IR in any cell type. IGF-I induced the release of the G(beta) subunits from the IGF-IR but had no effect on the association of G(alphai). These results demonstrate an association of heterotrimeric G(i) with the IGF-IR and identify a discrete pool of G(betagamma) subunits available for downstream signaling following stimulation with IGF-I.
Mesh Terms:
3T3 Cells, Animals, Enzyme Activation, GTP-Binding Protein alpha Subunits, Gi-Go, Humans, Mice, Mice, Inbred BALB C, Mice, Knockout, Mitogen-Activated Protein Kinases, Pertussis Toxin, Rats, Receptors, Somatomedin, Signal Transduction, Virulence Factors, Bordetella
J. Biol. Chem.
Date: Jan. 28, 2000
Download Curated Data For This Publication
3813
Switch View:
  • Interactions 1