Sherman, EilonBarr, ValarieManley, SulianaPatterson, GeorgeBalagopalan, LakshmiAkpan, ItoroRegan, Carole K.Merrill, Robert K.Sommers, Connie L.Lippincott-Schwartz, JenniferSamelson, Lawrence E.2012-04-272012-04-272012-04-27201110.1016/j.immuni.2011.10.004https://infoscience.epfl.ch/handle/20.500.14299/79729Receptor-regulated cellular signaling often is mediated by formation of transient, heterogeneous protein complexes of undefined structure. We used single and two-color photoactivated localization microscopy to study complexes downstream of the T cell antigen receptor (TCR) in single-molecule detail at the plasma membrane of intact T cells. The kinase ZAP-70 distributed completely with the TCRζ chain and both partially mixed with the adaptor LAT in activated cells, thus showing localized activation of LAT by TCR-coupled ZAP-70. In resting and activated cells, LAT primarily resided in nanoscale clusters as small as dimers whose formation depended on protein-protein and protein-lipid interactions. Surprisingly, the adaptor SLP-76 localized to the periphery of LAT clusters. This nanoscale structure depended on polymerized actin and its disruption affected TCR-dependent cell function. These results extend our understanding of the mechanism of T cell activation and the formation and organization of TCR-mediated signaling complexes, findings also relevant to other receptor systems. © 2011 Elsevier Inc.BIO-IMAGINGtext::journal::journal article::research article