Subcellular fractions were isolated by differential centrifugation from pure suspensions of human blood lymphocytes incubated with and without phytohemagglutinin (PHA). Between 30 and 120 min after addition of PHA to intact cells, redistribution of acid hydrolases (beta glucuronidase, acid phosphatase), from a 20,000 g x 20 min granular fraction into the corresponding supernatant, was observed....

A lysosomal pathway, characterized by the partial rupture or labilization of lysosomal membranes (LLM) and cathepsin release into the cytosol, is evoked during the early events of 20-S-camptothecin lactone (CPT)-induced apoptosis in human cancer cells, including human histiocytic lymphoma U-937 cells. These lysosomal events begin rapidly and simultaneously with mitochondrial permeabilization an...

Fas ligand (FasL) induces apoptosis through its cell surface receptor Fas. T lymphocytes and natural killer cells sort newly synthesised FasL to secretory lysosomes but, in cell types with conventional lysosomes, FasL appears directly on the plasma membrane. Here, we define a proline-rich domain (PRD) in the cytoplasmic tail of FasL that is responsible for sorting FasL to secretory lysosomes. D...

The effect of two gold(I) compounds on stability of lysosomes in vitro was studied. Lysosomes from homogenates of rat kidney cortex were isolated by differential centrifugation. These lysosomes were incubated at 37 degrees C with widely varied concentrations of sodium aurothiomalate and sodium aurothiosulphate for 5, 35, and 65 minutes. Acid phosphatase activities were measured and used as an i...

Lysosomes are acidic and highly dynamic organelles that are essential for macromolecule degradation and many other cellular functions. However, little is known about lysosomal function during early embryogenesis. Here, we found that the number of lysosomes increased after fertilization. Lysosomes were abundant during mouse preimplantation development until the morula stage, but their numbers de...

Cell-free systems have been successfully used to clarify some of the relationships between earlier parts of the endosomal system [ I , 21. The later stages of the process, by which endocytosed material appears in lysosomes for digestion, have received less attention. Indeed, the fundamental mechanism of this process is still in question. The maturation theory [ 31 holds that early endosomes are...

A combination of differential centrifugation and carrier-free continuous electrophoresis is introduced as a new method for the isolation of animal cell organelles. Various buffers were systematically checked in order to find the system which preserves the organelles and gives as well a good separation in the free-flow electrophoresis apparatus. Triethanolamine-acetate buffer (10 mM), pH 7.4 was...

The long-term exposure of macrophages to low concentrations of a number of polyanions leads to their accumulation in high concentration within secondary lysosomes. This was associated with enlargement of the lysosomes, the presence of membranous whorls, and intense toluidine blue staining of the organelles at pH 1.0. After the ingestion of a particulate load by these cells, newly formed phagocy...

We describe here the properties of a mutant of Chinese hamster ovary cells that expresses a conditional-lethal mutation affecting dense lysosomes. This mutant, termed V.24.1, is a member of the End4 complementation group of temperature-sensitive mutants selected for resistance to protein toxins (Colbaugh, P. A., C.-Y. Kao, S.-P. Shia, M. Stookey, and R. K. Draper. 1988. Somatic Cell Mol. Genet....

Lysosomes containing large amounts of the amino acid, cystine, were obtained from transformed, cultured, human lymphoblasts which had been exposed to cystine dimethyl ester. Lysosomal cystine efflux was greatly enhanced by exogenous ATP in cell lines from normal individuals. Cystine efflux was unresponsive to ATP in lysosomes from individuals with the disorder, cystinosis. Efflux of cystine fro...