Fig. 3

Phosphatase SHP-1 is the major intracellular TRAIL-R binding protein in TRAIL-R IP-MASS proteomics analysis. EL4 cells were transfected with plasmid encoding TRAIL-R, followed by stimulation with anti-CD3 (5 µg/mL) Ab for 30 min. Cell lysates were immunoprecipitated with an anti-TRAIL-R Ab, digested with trypsin, and subjected to LC–MS/MS. Proteins were identified, and scores were mapped using a Mascot MS/MS Ion Search. Protein scores were calculated as the sum of the highest ion scores for each peptide. a Ranking of putative TRAIL-R-interacting proteins in the order of protein scores. b Protein scores for SHP-1 and other major regulatory proteins involved in proximal TCR signaling