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Updated: Aug 13, 2026

Detection of Ligand-activated G Protein-coupled Receptor Internalization by Confocal Microscopy
10:24

Detection of Ligand-activated G Protein-coupled Receptor Internalization by Confocal Microscopy

Published on: April 9, 2017

RET ligand-induced internalization and its consequences for downstream signaling

D S Richardson1, A Z Lai, L M Mulligan

  • 1Department of Pathology and Molecular Medicine, Division of Cancer Biology and Genetics, Cancer Research Institute, Queen's University, Kingston, Ontario, Canada.

Oncogene
|January 19, 2006
PubMed

Insights

Ligand-induced internalization of RET receptor tyrosine kinase (RTK) is crucial for signal regulation. This process, dependent on RET kinase and dynamin 2, facilitates Erk1/2 activation.

Area of Science:

  • Cell Biology
  • Molecular Signaling
  • Receptor Tyrosine Kinases

Background:

  • RET receptor tyrosine kinase (RTK) regulates cell growth, differentiation, and survival.
  • Ligand binding activates RET, initiating signaling cascades like MAP kinase/Erk and PI3 kinase/Akt.
  • Mechanisms of RET internalization and signal downregulation remain largely unexplored.

Purpose of the Study:

  • To investigate the internalization process of RET following ligand-induced activation.
  • To determine the role of RET internalization in signal transduction and pathway regulation.
  • To elucidate the molecular machinery involved in RET trafficking and signaling termination.

Main Methods:

  • Utilized a fluorescence resonance energy transfer (FRET)-based assay to monitor RET internalization.
  • Assessed the requirement of RET kinase activity and dynamin 2 GTPase activity for internalization.
  • Investigated RET colocalization with Rab5a, a marker for clathrin-coated vesicles and early endosomes.
  • Analyzed the impact of RET internalization on Erk1/2 and Akt signaling pathway activation.

Main Results:

  • RET undergoes ligand-dependent internalization from the plasma membrane.
  • Internalization necessitates both RET kinase activity and the GTPase function of dynamin 2.
  • Internalized RET colocalizes with Rab5a, indicating trafficking through clathrin-coated vesicles and early endosomes.
  • RET internalization is essential for full Erk1/2 activation but not for Akt activation.

Conclusions:

  • Ligand-induced RET internalization is a critical mechanism for signal downregulation and termination.
  • Internalization facilitates RET trafficking to specific subcellular compartments for complete downstream signaling.
  • This process highlights a novel regulatory role for RTK internalization in modulating signal pathway activation.

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