Figure 1. LYP binds to CSK in an inducible manner.

A, Total lysates (TL) of HEK293 cells transiently transfected with LYP tagged with the myc epitope and HA-CSK, including the empty vector pEF as control, and treated or untreated with pervanadate (PV) for 5 min were subjected to immunoprecipitation (IP) and immunoblot (IB) with the indicated antibodies. B, Lysates from Jurkat cells transfected with plasmids that express myc-LYPR-DA or myc-LYPW-DA treated with PV for 5 minutes were subjected to IP with anti-myc Ab and then blotted with anti-HA (upper panel) to detect CSK. Similar expression of the proteins in the assay was detected by IB in the TL. C, Lysates of Jurkat cells untreated (resting cells), treated with PV or stimulated with anti-CD3 and anti-CD28 Abs for 5 min were subjected to IP with anti-CSK Ab, anti-LYP Ab, or an irrelevant Ab used as control, and inmunoblotted against endogenous LYP and CSK. D, T lymphocytes obtained from peripheral blood of healthy donors were incubated for the indicated times at 37°C with medium alone or in the presence of anti-CD3 and anti-CD28 Ab. Lysates from these cells were immunoprecipitated with anti-CSK or an irrelevant Ab (IgG) to show specificity, and the presence of LYP and CSK in the precipitates was detected with specific Abs by IB. LYP blot was measured by densitometry and the values obtained, shown under the blot, are expressed in arbitrary units.