Plasma membrane subdomain partitioning of Lck in primary human T lymphocytes.
Uncovering the plasma membrane distribution of tyrosine kinase Lck is crucial to understanding T lymphocyte triggering. Several studies of Lck species partitioning have given contradictory results. We decided to re-address this point by using phospho-specific antibodies to characterize active and inactive Lck partitioning in raft and non-raft membranes from primary human peripheral blood T lymphocytes. We show that most inactive Lck was localized in rafts and was associated with nearly all CD4 coreceptors and its negative regulator Csk in resting cells, while T cell receptor (TCR) engagement promoted a sustained dephosphorylation of inactive Lck. In contrast, active Lck had a more discrete distribution interacting with only a small number of CD4 coreceptors, and the kinase showed a rapid and short phosphorylation after TCR triggering. The differences in distribution and kinetics may be related to T lymphocyte signalling threshold modulation by Lck species and suggest how TCR triggering is first initiated. This study furthers our knowledge of the TCR activation model in primary human T lymphocytes.
Irles
Claudine
C
Departamento de Bioquímica y Biología Molecular, Instituto Nacional de Perinatologia "Isidro Espinoza de los Reyes", México D.F, C.P. 11000, México.
Arias-Martinez
Joel
J
Guzmán-Bárcenas
José
J
Ortega
Alicia
A
D002462:Cell Membrane / Q000201:enzymology*; D006801:Humans; D047468:Immunoprecipitation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism*; D021962:Membrane Microdomains / Q000201:enzymology* / Q000378:metabolism; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology
D011948:Receptors, Antigen, T-Cell; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)