Fig. 4.

DSP4-GST binding to starch in vitro. (A) Protein alignment of starch-binding domains of Homo sapiens laforin (NP_005661) and DSP4. Conserved residues involved in binding are highlighted. (B) Starch-binding of DSP4 and its dependence on pH. The total GST-DSP4 used in the binding assay was used as a loading control (Ctr). (C) Starch binding of GST-DSP4 in 50 mM Tris, pH 7.5 (Ctr); of catalytically inactive DSP4 (C198A); and of GST-DSP4 in presence of 1.0 mM H₂O₂ or 5.0 mM GSSG. “So” denotes the soluble phase (supernatant), and “St” denotes the starch pellets. Similar results were obtained with His6x-DSP4 protein and His6x antibody (not shown).