Glutaminase activity of PDX2. A, Initial rates of PDX2 glutaminase activity either in the absence of PDX1 (dashed and dotted line) or in the presence of PDX1.1 (solid line), PDX1.2 (dotted line), or PDX1.3 (dashed line). In every case, 10 μm of each protein and 20 mm Gln was used. B, Rate of PDX2 (10 μm) glutaminase activity as a function of the concentration of PDX1.1 (molar ratio 0–3.0).