Figure 1. Electrophoretic mobility shift assay of double-stranded polynucleotides with different chain lengths in the presence of tau protein.

Double-stranded polynucleotides (100 ng) with different chain lengths (as indicated in each lane and Table 1) were incubated with tau23 at a ratio [protein]/[DNA] of 1/10 in the buffer of 20 mM Tris-HCl (pH 7.2), containing 50 mM NaCl, 0.5 mM DTT, 1 mM MgCl₂ and 0.5 mM EDTA at room temperature for 30 min, and then aliquots were taken for electrophoresis on a nondenaturing 20% polyacrylamide gel (A). The polynucleotides without tau protein were used as controls under the same experimental conditions (B).