Figure 3.

Removal of ³²P from the 43-kDa protein by NaBH₄. The 43-kDa protein in the Blue Sepharose fraction was phosphorylated by incubation with 0.6 μM [³²P]NDPK for 10 min at room temperature. The proteins were precipitated on ice in 16% trichloroacetic acid. The protein pellets were rinsed with 1 ml of cold 10 mM HCl and dried under vacuum. The pellets were dissolved in dimethyl sulfoxide and incubated at room temperature in the presence and absence of 25 mM NaBH₄ (30). After 5 or 60 min, SDS sample buffer was added, and the samples analyzed by SDS/PAGE and autoradiography. The lower panel shows a shorter exposure of the autoradiogram of the part of the gel containing [³²P]NDPK.