Endo- and exocytic rate constants for spontaneous and protein kinase C-activated T cell receptor cycling

Eur J Immunol. 2002 Mar;32(3):616-26. doi: 10.1002/1521-4141(200203)32:3<616::aid-immu616>3.3.co;2-0.


To determine the rate constants of spontaneous and activated TCR cycling, we examined TCR endo- and exocytosis in the human T cell line Jurkat by three different methods. Using a simple kinetic model for TCR cycling and non-linear regression analyses, we found that the spontaneous endocytic rate constant of the TCR was low (approximately 0.012 min(-1)) whereas the spontaneous exocytic rate constant was similar to that of other cycling receptors (approximately 0.055 min(-1)). Following protein kinase C activation (PKC) the endocytic rate constant was increased tenfold (to approximately 0.128 min(-1)) whereas the exocytic rate constant was unaffected. Thus, the TCR becomes a rapidly cycling receptor with kinetics similar to classical cycling receptors subsequent to PKC activation. This results in a reduction of the half-life of cell surface expressed TCR from approximately 58 to 6 min and allows rapid redistribution of the TCR during T cell activation.

Publication types

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

MeSH terms

  • Amino Acid Motifs
  • Antibodies, Monoclonal / metabolism
  • CD3 Complex / metabolism
  • Down-Regulation
  • Endocytosis* / drug effects
  • Enzyme Activation
  • Exocytosis* / drug effects
  • Fluorescein-5-isothiocyanate / metabolism
  • Fluorescent Dyes / metabolism
  • Humans
  • Jurkat Cells / drug effects
  • Jurkat Cells / metabolism
  • Kinetics
  • Phosphorylation
  • Protein Kinase C / pharmacology*
  • Protein Processing, Post-Translational
  • Receptors, Antigen, T-Cell / metabolism*
  • Up-Regulation


  • Antibodies, Monoclonal
  • CD3 Complex
  • CD3 antigen, gamma chain
  • Fluorescent Dyes
  • Receptors, Antigen, T-Cell
  • Protein Kinase C
  • Fluorescein-5-isothiocyanate