Atypical G(αi) signal transduction

Curr Vasc Pharmacol. 2014 Mar;12(2):258-70. doi: 10.2174/1570161112666140226122512.

Abstract

G protein signaling is an extremely complex event that is involved in almost every cellular process. As such, G protein-coupled receptors are the most commonly found type of transmembrane receptors used by cells to initiate intracellular signaling events. However, the widely accepted model of cyclical GDP-GTP exchange in response to ligand binding to 7TMRs, followed by dissociation of the G protein subunits and activation of intracellular signaling cascades, has repeatedly been challenged in recent years. Some of the exceptions that have been brought forth include signaling by a non-dissociated, rearranged heterotrimer and the existence of "reverse-mode", active G proteins that interact with active receptors. Here, we focus on G(αi/o), one of the common G(α) classes, and outline a major exception to the classical model, that of G protein coupling to RTKs. We then describe a novel concept in G(αi/o) signaling, namely that the pathways induced by agonist binding circumvent the typical signaling pathways responsive to decreases in the second messenger cAMP, via adenylyl cyclase inhibition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins / physiology
  • Caveolins / physiology
  • ErbB Receptors / physiology
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels / physiology
  • GTP-Binding Protein alpha Subunits, Gi-Go / physiology*
  • Humans
  • Microfilament Proteins / physiology
  • Receptor, Insulin / physiology
  • Receptors, Vascular Endothelial Growth Factor / physiology
  • Signal Transduction / physiology*
  • TRPC Cation Channels / physiology
  • Vesicular Transport Proteins / physiology

Substances

  • Apoptosis Regulatory Proteins
  • CCDC88A protein, human
  • Caveolins
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • Microfilament Proteins
  • TNFAIP8 protein, human
  • TRPC Cation Channels
  • TRPC4 ion channel
  • Vesicular Transport Proteins
  • ErbB Receptors
  • Receptor, Insulin
  • Receptors, Vascular Endothelial Growth Factor
  • GTP-Binding Protein alpha Subunits, Gi-Go