The Properties and Subcellular Localization of Acid Phosphatases in the Colourless Alga, Polytomella Caeca

Abstract

The acid p-nitrophenyl phosphatase of homogenates of Polytomella caeca is a latent acid hydrolase, which is partially inhibited by NaF. Its distribution profile in density gradients (which is similar to that of naphthyl AS-TR phosphatase) suggests that this enzyme is partially lysosomal in location. Cytochemical evidence for the localization of acid phosphatases in fine subcellular structures is presented. Naphthyl AS-TR phosphatase is localized in vacuoles, points of focal degradation, Golgi bodies and dispersed throughout the cytosol. β-Glycerophosphatase is confined to large vacuoles and the cytosol. The nature of acid phosphatase-containing organelles in P. caeca is discussed in view of the inability to detect eleven other latent acid hydrolases in cell-free homogenates.