We report experiments to investigate the role of the physio-logically relevant protein tyrosine kinase Lck in the ordered phosphorylation of the T-cell receptorfchain. Six synthetic peptides were designed based on the sequences of the immunoreceptor tyrosine-based activation motifs (ITAMs) of thefchain. Preliminary 1 H-NMRstudies of recombinant f chain suggested that it is essentially unstructured and therefore that peptide mimics would serve as useful models for investigating individual ITAM tyrosines
