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Updated: Aug 6, 2026

A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins
16:10

A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins

Published on: March 22, 2012

T-cell antigen receptor-induced signaling complexes: internalization via a cholesterol-dependent endocytic pathway

Valarie A Barr1, Lakshmi Balagopalan, Mira Barda-Saad

  • 1Laboratory of Cellular and Molecular Biology, Department of Health and Human Services, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.

Traffic (Copenhagen, Denmark)
|August 22, 2006
PubMed

Insights

T-cell receptor (TCR) engagement triggers the endocytosis of signaling proteins like SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) and LAT (linker for activation of T-cells). This internalization, dependent on lipid rafts and ubiquitination, may downregulate TCR signaling.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • T-cell receptor (TCR) engagement initiates rapid assembly of intracellular signaling complexes.
  • Adapter proteins, such as SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa), play crucial roles in TCR signaling pathways.

Purpose of the Study:

  • To investigate the dynamic movement and internalization mechanism of SLP-76 following TCR engagement.
  • To elucidate the role of lipid rafts and protein ubiquitination in SLP-76 trafficking and TCR signaling regulation.

Main Methods:

  • Total internal reflection fluorescence microscopy (TIRFM) to observe protein dynamics.
  • Immunoelectron microscopy to visualize subcellular localization.
  • Functional assays involving cholesterol depletion and protein domain co-expression.

Main Results:

  • SLP-76 initially clusters with the TCR and translocates on microtubules, requiring endocytosis.
  • SLP-76 internalization occurs via smooth pits and tubules, dependent on lipid rafts and interaction with ubiquitinated proteins.
  • Endocytosed SLP-76 clusters contain phosphorylated SLP-76 and LAT (linker for activation of T-cells), suggesting raft-dependent targeting to endocytic vesicles.

Conclusions:

  • TCR activation induces a lipid raft-dependent endocytosis pathway for SLP-76 and LAT.
  • This endocytic mechanism involving ubiquitination may serve to downregulate TCR signaling complexes.

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