Spherical electron-dense organelles in the perinuclear region of cultured guinea pig aortic smooth muscle cells were identified as lysosomes by their ability to accumulate acridine orange and by cytochemical demonstration of their acid phosphatase content. The number and size of lysosomes increased in subcultured cells. The elemental composition of the lysosomes was quantitated by electron prob...

Lysosomes are organelles of eukaryotic cells that are critically involved in the degradation of macromolecules mainly delivered by endocytosis and autophagocytosis. Degradation is achieved by more than 60 hydrolases sequestered by a single phospholipid bilayer. The lysosomal membrane facilitates interaction and fusion with other compartments and harbours transport proteins catalysing the export...

The density-distribution patterns of various enzymes and of labeled materials have been determined by isopycnic centrifugation in a sucrose-0.2 M KCl gradient on homogenates of lymphoid tissues from rats injected with Triton WR-1339, (14)C-labeled dextran, (51)Cr-labeled erythrocytes, and cortisol. The results confirm and extend the conclusion, derived from previous investigations on normal ani...

The effect of colchicine injections on the ultrastructural localization of dipeptidyl peptidase II (Dpp II) was studied in the mitral cells of the rat olfactory bulb. In control animals, electron-dense reaction product representing Dpp II activity was observed in lysosomes, lipofuscin granules, short cisternae located close to the granular endoplasmic reticulum, and dense granules. Lysosomes an...

Deficiencies in protein degradation and proteolytic function within neurons are linked to a number of neurodegenerative diseases and developmental disorders. Compartmentalized cultures of peripheral neurons were used to investigate the properties and relative abundance of the proteolytic machinery in the axons and cell bodies of sympathetic and sensory neurons. Immunoblotting of axonal proteins...

Regulation of the cytosolic free calcium concentration is important to neutrophil function. In these studies, an ATP-dependent calcium uptake pump has been identified in human neutrophil lysosomes. This energy-dependent Ca++ uptake pump has a high affinity for Ca++ (Michaelis constant [Km] Ca++ = 107 nM) and a maximum velocity (Vmax) of 5.3 pmol/mg of protein per min. ATP was the only nucleotid...

Incubation of kidney lysosomes at 37 degrees results in a graded release of lysosomal enzymes. The release of enzyme occurs in two stages. First the enzymes become available to the substrate but remain sedimentable. Later the amount of soluble enzyme increases and eventually is almost equal to that of the available enzyme. Morphological studies of lysosomes showed that during the process involv...

Lysosomal cystine transport is a carrier-dependent process that, in isolated lysosomes, is stimulated by proton gradients, membrane potential, and millimolar concentrations of divalent cations. The importance of these regulatory factors in vivo is not well established. Polyamines were found to stimulate cystine transport in Percoll gradient purified rat liver lysosomes with spermidine greater t...

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 phagoc...

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 w...