The effect of phytochrome action on the activity of cytosolic cholinesterase in oat cells.

ABSTRACT

Cholinesterases in the oat cell were found to be distributed in the cell wall (50%) and cytoplasm (42%). Activity of the cytosolic enzyme was inhibited about 80% by 1 mM Ca2+. The enzyme activity was also inhibited by Mn2+, but no inhibition by Mg2+ was observed. Effects of red light and calcium ion on the enzyme activity were investigated in vivo to confirm the involvement of phytochrome action in the regulation process of this enzyme via Ca2+. It was observed that inhibition by red light only occurs when external Ca2+ existed in the cell medium. Based on a previous report (8) that red light stimulates the influx of Ca2+ into the cytosol of oat cell, inhibition of the enzyme activity by irradiation of red light can be suggested to occur via the influx of Ca2+.