Figure 4.

Cation dependence for autophosphorylation of ETR1. GST fusions with either ETR1(164–738) or ETR1(164–609) were examined for autophosphorylation in the presence of various cations (³²P). Wild-type (WT) and the His-353–Gln (H) site-directed mutation of ETR1 were tested with 5 mM MnCl₂, 5 mM MgCl₂, 5 mM CaCl₂, or a mixture of 5 mM MnCl₂ and 5 mM MgCl₂. After autoradiography, the presence of each fusion protein was confirmed by Western blot using a polyclonal antibody directed against GST (Ab).