An evolutionary and structural perspective on T cell antigen receptor function

After a brief overview of the themes and variations that occur in the family of receptors containing immunoreceptor tyrosine-based activation motifs (ITAMs), and of recent structural data on the ligand-binding subunits of these receptors, we use these data to revisit how information on the state and quality of occupancy of the binding site of the T cell antigen receptor (TCR) is conveyed to the proximal components of the TCR transduction cassette.