Evidence for acidity of prelysosomal autophagic/endocytic vacuoles (amphisomes).
[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.
Strømhaug
P E
PE
Department of Tissue Culture, Norwegian Radium Hospital, Oslo.
Seglen
P O
PO
D000818:Animals; D001216:Asparagine / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects; D004705:Endocytosis; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D008099:Liver / Q000648:ultrastructure*; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D011437:Propylamines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014617:Vacuoles / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D011437:Propylamines; D001216:Asparagine; D001616:beta-Galactosidase; D007785:Lactose