A mechanism for intralysosomal membrane recycling is proposed. After invagination of the lysosomal membrane during autophagy, intralysosomal vesicles are formed. It is suggested that membrane can bleb out from these internal vesicles, probably in the form of very small vesicles, and return to the external lysosomal membrane by membrane fusion. This mechanism would conserve lysosomal membrane du...

Antisera to rabbit polymorph granules and to rabbit erythrocytes have been prepared in guinea pigs. Both antigranule and antierythrocyte sera are hemolytic and both exhibit striking cytotoxicity on leucocytes. The sequence of toxic events, as observed by phase contrast cinemicrophotography and electron microscopy, consists of explosive granule lysis, cell swelling, cytoplasmic liquifaction, and...

Similar to its role in secretory cells, calcium triggers exocytosis in nonsecretory cells. This calcium-dependent exocytosis is essential for repair of membrane ruptures. Using total internal reflection fluorescence microscopy, we observed that many organelles implicated in this process, including ER, post-Golgi vesicles, late endosomes, early endosomes, and lysosomes, were within 100 nm of the...

This protocol describes the generation of a fraction enriched in lysosomes from rat liver. The lysosomes are rapidly isolated using density-gradient centrifugation with gradient media that retain the osmolarity of the lysosomes such that they are functional and can be used in in vitro assays.

Lipids are essential components of a cell providing energy substrates for cellular processes, signaling intermediates, and building blocks for biological membranes. Lipids are constantly recycled and redistributed within a cell. Lysosomes play an important role in this recycling process that involves the recruitment of lipids to lysosomes via autophagy or endocytosis for their degradation by ly...

1982). It is not clear how the rate of entry into lysosomes themselves is affected, but it may be retarded. The situation is even more obscure in the case of entry into lysosomes by autophagy. There are some indications of abnormalities in endogenous protein breakdown, and in perhaps of the lysosomal component thereof, in I-cell disease (Cockle & Dean, 1984). Similarly, Sameshima et al. (1981) ...

174 The invention of freeze fracture EM and the determination of membrane structure Catching sight of lysosomes ll we wanted was to know something about the localization of glucose-6phosphatase, which we thought might provide a possible clue to the mechanism of action, or lack of action, of insulin on the liver cell.” Thus begins Christian de Duve’s discovery of lysosomes, which he first visual...

cytes. Both androstenedione and progesterone, 10 -10' M, caused leakage of acid hydrolase markers from these organelles, thus resembling their effects on liver lysosomes. But none of the anti-inflammatory steroids tested protected organelle membranes from either detergent lysis (Triton X-100) or heat incubation (37GC, 90 min). Hydrocortisone (HC), HC sodium succinate, HC acetate, HC hemisuccina...