title: Endo- and exocytic rate constants for spontaneous and protein kinase C-activated T cell receptor cycling.
abstract: 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.
authors.affiliation: Institute of Medical Microbiology and Immunology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Menné
authors.forename: Tine
authors.initials: T
authors.lastname: Møller Sørensen
authors.forename: Volkert
authors.initials: V
authors.lastname: Siersma
authors.forename: Marina
authors.initials: M
authors.lastname: von Essen
authors.forename: Niels
authors.initials: N
authors.lastname: Ødum
authors.forename: Carsten
authors.initials: C
authors.lastname: Geisler
mesh_terms: D020816:Amino Acid Motifs; D000911:Antibodies, Monoclonal / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D015536:Down-Regulation; D004705:Endocytosis / Q000187:drug effects; D004789:Enzyme Activation; D005089:Exocytosis / Q000187:drug effects; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D010766:Phosphorylation; D011493:Protein Kinase C / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; C452842:CD3 antigen, gamma chain; D005456:Fluorescent Dyes; D011948:Receptors, Antigen, T-Cell; D011493:Protein Kinase C; D016650:Fluorescein-5-isothiocyanate