Figure 5.

pH dependence for autophosphorylation of ETR1. GST-ETR1(333–609) was incubated with ³²P-ATP at the indicated pH, subjected to SDS/PAGE, and transferred to nylon membrane. Alkali-resistant phosphate was visualized by autoradiography and quantified densitometrically. For pH 4.9 to 6.9 (•), the kinase assay mixture was buffered with 50 mM Mes, 100 mM Tris. For pH 6.9 to 8.3 (○), the kinase assay mixture was buffered with 100 mM Tris. The data were fit to a sigmoidal curve using sigmaplot. Data points represent the mean of duplicate samples.