Competitive effect of oxidized and nonoxidized cdbd3 on band 3 phosphorylation and its association with Syk. Band 3 Tyr phosphorylation was measured in membranes obtained from diamide treated RBCs in the presence of RBC cytoplasm at increasing concentration of oxidized or nonoxidized cdbd3. The level of band 3 phosphorylation is displayed as percentage of its maximal phosphorylation absence of cdbd3 (panel (a)). Nonoxidized (−Dia) cdbd3 and oxidized (+Dia) cdbd3 were incubated with RBC cytoplasm and immunoprecipitated by anti-cdbd3 antibody. Immunoprecipitated proteins were western blotted with anti-band 3 (panel (a)) and anti-Syk antibody (panel (b)). Western blots are representative of 4 separated experiments.