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A Tiedtke

Publications and source records attributed to A Tiedtke.

24 records · Page 2Linked to original sources
PubMed1983

Acid phosphatase associated with discharging secretory vesicles (mucocysts) of Tetrahymena thermophila.

The localization of acid phosphatase in discharging mucocysts of Tetrahymena thermophila is reported. Electron dense, lead phosphate enzyme reaction product is found associated with the fibrillar meshwork of secreting mucocysts and in cytoplasmic vesicles (e.g. lysosomes). Resting mucocysts, containing highly condensed contents, exhibit no label. The specificity of the stain was controlled by reaction media without exogenous substrate and reaction media containing the inhibitor sodium fluoride. No lead phosphate deposits were found in these controls. Secreting organelle contents have no preferential affinity to lead phosphate as shown by tests with reaction medium lacking substrate and subsequent incubation in phosphate containing medium.

Acid Phosphatase↗
PubMedDate not supplied

Biochemical analysis of membrane proteins from an early maturation stage of phagosomes.

We used an improved technique for pulse-chase labeling of phagosomes using custom-made magnetic microparticles. With the help of a permanent magnet we purified both newly formed, nascent and early matured (i.e., 5-min-old) condensed phagosomes in high amounts. The protein patterns of membrane proteins of newly formed phagosomes and 5-min-old condensed ones were compared by two-dimensional (2-D) electrophoresis. The protein patterns allowed the detection of protein spots that changed in abundance between these two stages. Three protein spots abundant in condensed phagosomes only and one spot well-stained in both stages were collected from ten preparative Coomassie brilliant blue-stained 2-D gels. Following microdigestion, selected purified oligopeptides were sequenced by Edman degradation. While the oligopeptide sequences of proteins from two spots showed high homology to an already sequenced 25 kDa calcium binding protein, the other two showed no significant homology to protein sequences available in sequence databases. Presently polymerase chain reaction (PCR) and cloning experiments are set up to reveal the cDNAs of these proteins in order to study their function by knock-out and gene replacement experiments.

Amino Acid Sequence↗
PubMedDate not supplied

The Golgi apparatus of Tetrahymena thermophila.

Electron microscopic investigations reveal that the Golgi apparatus of Tetrahymena thermophila consists of numerous tiny dictyosomes, each consisting of one or two cisternae. The dictyosomes are localized predominantly in the cell cortex closely associated with the mitochondria, arranged in meridians alternating with the ciliary meridians. We estimated about 300-400 of these dictyosomes in the periphery of a cell, a value corresponding to the number of somatic cilia per cell. Cytochemical assays of thiamine pyrophosphatase and acid phosphatase, both marker enzymes of trans Golgi cisternae, resulted in deposits of lead or cerium phosphate in the outermost cisternae of the dictyosomes. In addition, cisternae located at the bases of the basal body/parasomal sac arrangements are stained. This indicates that these cisternae may belong to the Golgi apparatus of the cell.

Acid Phosphatase↗
PubMedDate not supplied

Processing and secretion of lysosomal acid alpha-glucosidase in Tetrahymena wild type and secretion-deficient mutant cells.

The proteolytic processing and secretion of a lysosomal enzyme, acid alpha-glucosidase, was studied by pulse-chase labeling with [35S]methionine in Tetrahymena thermophila CU-399 cells treated with ammonium chloride. This cell secreted a large amount of acid alpha-glucosidase into the cultured medium during starvation. The secretion was found to be repressed by addition of ammonium chloride (NH4Cl). Acid alpha-glucosidase was produced as a precursor form (108 kDa) and then processed to a mature polypeptide (105 kDa) within 60 min. This mature enzyme was secreted into the media within 2-3 h after chase, whereas the precursor form was not secreted by either control cells or NH4Cl-treated cells. NH4Cl did not affect the processing of the precursor acid alpha-glucosidase. Processing profile of this enzyme was apparently indistinguishable from that of the mutant MS-1 defective in lysosomal enzyme secretion. Furthermore, the purified extracellular (CU-399) and intracellular (MS-1) acid alpha-glucosidases were the same in molecular mass (105 kDa) and enzymatic properties. They contained no mannose 6-phosphate residues in N-linked oligosaccharides. These results suggested that unlike mammalian cells, Tetrahymena acid alpha-glucosidase may be transferred to lysosomes by a mannose 6-phosphate receptor-independent mechanism, and also that low pH was not essential for the proteolytic processing of precursor polypeptide.

Ammonium Chloride↗