Affinity isolation and identification by mass spectrometry of proteins from IC2 cells that associate with synthetic Shc phosphopeptides.

Immobilized biotinylated phosphopeptides pY239Y (lane 1), YpY240 (lane 2), pY239pY240 (lane 3), and pY317 (lane 4) were incubated with IC2 cell lysates. Bound proteins were eluted by phenyl phosphate and analyzed in a silver-stained gel. Bands identified as Grb2 (accession number Q60631), Sos1 (accession number Q62245), the p85 subunit of phosphatidylinositol 3′ kinase (accession number P26450), and SHIP (accession number U39203) are marked.