Issues

Cover picture: Association of LAT with CD4 and CD8 coreceptor molecules defines a new coreceptor function in T cell antigen receptor (TCR) signal transduction. A previously known function performed by coreceptor molecules that have bound the same MHC­peptide complexes as TCR is the juxtaposition of Lck with tyrosine phosphorylation sites in the cytosolic tail of TCR proteins, resulting in immunoreceptor tyrosine-activated motif (ITAM) phosphorylation and recruitment of ZAP-70 to surface TCR complexes. A newly discovered function performed by coreceptor molecules that have bound the same MHC­peptide complexes as TCR is the juxtaposition of the linker molecule LAT with surface TCR complexes, promoting LAT¹s phosphorylation by TCR-bound ZAP-70 molecules. Phosphorylated LAT molecules then recruit signaling intermediates necessary for further propagation of the TCR signal. See related article in this issue by Bosselut et al., 1517-15525.