Evidence for acidity of prelysosomal autophagic/endocytic vacuoles (amphisomes)

• Published in: Biochemical journal Vol. 291; no. 1; pp. 115 - 121
• Main Authors: STRØMHAUG, P. E, SEGLEN, P. O
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 01-04-1993
• Subjects: Animals; Asparagine - pharmacology; Autophagy - drug effects; beta-Galactosidase - metabolism; Biological and medical sciences; Cell structures and functions; Endocytosis; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Lactose - metabolism; Liver - ultrastructure; Lysosome, phagosome; Lysosomes - metabolism; Male; Molecular and cellular biology; Propylamines - pharmacology; Rats; Rats, Wistar; Vacuoles - metabolism; Rat; Enzyme; Rodentia; Lysosome; Galactosidase; Acidity; Vertebrata; Endocytosis; Lactose; Mammalia; Hepatocyte; Biological accumulation; Phagocytosis
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2910115

[14C]Lactose electroinjected into isolated rat hepatocytes is normally autophagocytosed, transferred to lysosomes and degraded by lysosomal beta-galactosidase, but at high concentrations of asparagine the transfer is inhibited and lactose accumulates in prelysosomal autophagic/endocytic vacuoles (amphisomes). The accumulation can be prevented by addition of yeast beta-galactosidase, which is transferred to the lactose-containing vacuoles by endocytosis. Propylamine, a weak base capable of neutralizing acidic vacuoles, protects autophagocytosed lactose against both endogenous and exogenous beta-galactosidase, suggesting that amphisomes, like lysosomes, have an acidic internal environment.