Sucrose starvation causes a loss of immunologically detectable pyrophosphatase and V-ATPase in the tonoplast of suspension-cultured tobacco cells

Abstract

Summary The effect of sucrose starvation on logarithmically growing suspension cultures of tobacco BY-2 cells has been investigated by immunogold electron microscopy with antisera against pyrophosphatase (PPase) and V-ATPase. In normal cells PPase is located at the plasma and tonoplast membranes, whereas V-ATPase is restricted to the tonoplast. After 32 h of growth in the absence of exogenous sucrose, both PPase and V-ATPase polypeptides are no longer detectable in the tonoplast by this method. By contrast, plasma membrane-bound PPase appears to be unaffected by sucrose deficiency. These results are discussed in terms of a down-regulation of electrogenic pumps in the tonoplast.