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.