Comparison of Hevea Tonoplast Adenosine-triphosphatase from Freshly Isolated Vacuoles and Lyophilized Tonoplast Vesicles

There is no significant difference between the ATPase present in the Hevea tonoplast of freshly isolated vacuoles and of lyophilized tonoplast vesicles (same k_m value for MgATP^2-, same pH-dependence, same effect of inhibitors, same effect of ionophores and protonophores).

It is suggested that the components of the protonmotive force regulate the activity of the tonoplast H⁺-translocating ATPase. The consequences of such effects may be very important in the regulation of events linked to the compartmentation of solutes inside the plant cell.