passages.id: split_9_validation_1397_passage
passages.type: progene_text
passages.text: Lck from APB CD4 + T-cell blasts bound the peptide containing the phosphotyrosine at the negative regulatory site of Lck - 505 indicating that the site of dephosphorylation in TSST-1 - activated T-cell blasts is Tyr - 505 .