Analysis of the Distribution of Potassium-stimulated Adenosine Triphosphatase Activity in Soybean Root

Abstract

The distribution of activity of a potassium-stimulated ATPase associated with the plasma membrane was determined in 4 day old soybean [Glycine max cv. Wells] roots. Changes in protein-based specific activity of the enzyme coincided with developmental changes in the root. Activity was low in the region of the root cap, increased to a maximum in the meristematic region, decreased to a minimum as cell elongation proceeded and then increased as lateral root development began. Analysis of the data indicated that fluctuations in enzyme activity were described by a 3-phase system which was approximated by a linear-linear-linear piece-wise regression curve. The need for constructing a biological model to described plasma membrane development is suggested.