CD43-induced stimulation of PYK-2 tyrosine kinase activity. (A) NK cells were allowed to adhere for 60 minutes, on dishes precoated with BSA, with the HP 2/9 anti-CD44 MoAb, TP 1/36 anti-CD43 MoAb, or TP1/36 F(ab′)2 fragments. Cells were then lysed and the extracts were incubated with C-19 antibody to immunoprecipitate PYK-2 (C-19) or with nonimmune serum (NIS) control and in vitro kinase reactions, performed as described in Materials and Methods (IVK, top). PYK-2 levels were determined by immunoprecipitation with the C-19 anti-PYK-2 antibody and Western blot analysis with C-19 anti–PYK-2 antibody (IP: C-19; WB: C-19; bottom). The position of PYK-2 is indicated with an arrow. (B) Quantification by densitometric scanning of the effect of stimulation with BSA, anti-CD44, and anti-CD43 on PYK-2 activity. PYK-2 was immunoprecipitated with the C-19 antibody and in vitro kinase reactions performed as described in Materials and Methods. Values are the mean± SEM of 5 independent experiments and are expressed as fold-stimulation above control. (C) NK cells were allowed to adhere for 60 minutes on dishes precoated with BSA or TP1/36 F(ab′)2 fragments. Cells were then lysed and processed as described above.
