Figure 8.

Enhancement of C-terminal negative regulatory residue (Tyr507) phosphorylation of Lyn kinase by Jacalin through inhibition of CD45 protein tyrosine phosphatase (PTPase) activity in Raji B cells. Raji B cells were treated with Jacalin at 50 μg/ml in the absence or presence of the PTPase CD45 inhibitor (1 μm) for 3 hr, followed by assessment of tyrosine phosphorylation of Lyn kinase. The levels of Lyn phosphorylated at tyrosine 507 and 396 and total 56 000 Lyn were determined by Western blotting with specific antibodies against phospho-Lyn (Tyr507), phospho-Lyn (Tyr396) and total Lyn, respectively. The arrows indicate phospho-Lyn (Tyr507) (upper panel), phospho-Lyn (Tyr396) (middle panel) and total 56 kDa Lyn (lower panel). GAPDH expression was examined as a loading control (bottom panel). The results are representative of three independent experiments.