Figure 1.

Altered Tyr phosphorylation by the addition of heparin. 293 cells expressing GFP (lanes 1), RPTPσ (lanes 2), and RPTPσ ΔLys (lanes 3) were treated with heparin (1 mg/ml) for the indicated times (A) and different concentrations of heparin for 5 (B) and 30 min (C). Proteins were separated by SDS-PAGE followed by immunoblotting with anti-phosphotyrosine antibody. D, cells were treated with heparin, CS-E, and DS (1 mg/ml) for 5 min. Similar expression levels of recombinant proteins were confirmed with anti-His₆ tag antibody (Fig. S2). Cont, control; TM, transmembrane.