Self-non-self discrimination is central to T cell-mediated immunity. The kinetic proofreading model can explain T cell antigen receptor (TCR) ligand discrimination; however, the rate-limiting steps have not been identified. Here, we show that tyrosine phosphorylation of the T cell adapter protein LAT at position Y132 is a critical kinetic bottleneck for ligand discrimination. LAT phosphorylation at Y132, mediated by the kinase ZAP-70, leads to the recruitment and activation of phospholipase C-γ1 (PLC-γ1), an important effector molecule for T cell activation. The slow phosphorylation of Y132, relative to other phosphosites on LAT, is governed by a preceding glycine residue (G131) but can be accelerated by substituting this glycine with aspartate or glutamate. Acceleration of Y132 phosphorylation increases the speed and magnitude of PLC-γ1 activation and enhances T cell sensitivity to weaker stimuli, including weak agonists and self-peptides. These observations suggest that the slow phosphorylation of Y132 acts as a proofreading step to facilitate T cell ligand discrimination.

• MeSH
• adaptorové proteiny signální transdukční imunologie   metabolismus   MeSH
• aktivace lymfocytů * MeSH
• fosfolipasa C gama metabolismus   MeSH
• fosforylace imunologie   MeSH
• ligandy MeSH
• membránové proteiny imunologie   metabolismus   MeSH
• myši MeSH
• protein-tyrosinkináza ZAP-70 metabolismus   MeSH
• receptory antigenů T-buněk imunologie   metabolismus   MeSH
• T-lymfocyty imunologie   metabolismus   MeSH
• tyrosin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH