Biomaterial Database

Evidence for penetration of diphtheria toxin to the cytosol through a prelysosomal membrane. 1984

M H Marnell, and S P Shia, and M Stookey, and R K Draper

To kill mammalian cells, diphtheria toxin must be endocytosed and encounter a low pH within intracellular vesicles. The low pH initiates penetration of the catalytically active A fragment of the toxin through a membrane and into the cytosol where the A fragment arrests protein synthesis. To investigate whether penetration occurred through a prelysosomal or a lysosomal membrane, we studied the effect of low temperature on the entry of the toxin into the cytosolic and lysosomal compartments. The toxin arrested protein synthesis at 15 degrees C, indicating entry into the cytosol; however, access to lysosomes was apparently blocked at 15 degrees C, suggesting that the toxin had encountered a low pH before reaching lysosomes and had penetrated a prelysosomal membrane. To further investigate the possibility of prelysosomal acidification, we measured the time required for the toxin to encounter a low pH after endocytosis. Acidification occurred within 3 to 4 min after the toxin was internalized into vesicles. This interval is consistent with prelysosomal acidification since the entry of endocytosed ligands into secondary lysosomes usually takes more than 3 to 4 min.

UI	MeSH Term	Description	Entries
D007425	Intracellular Membranes	Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.	Membranes, Intracellular,Intracellular Membrane,Membrane, Intracellular
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008247	Lysosomes	A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes MEMBRANE FUSION. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed).	Autolysosome,Autolysosomes,Lysosome
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D002522	Chlorocebus aethiops	A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.	African Green Monkey,Cercopithecus aethiops,Cercopithecus griseoviridis,Cercopithecus griseus,Cercopithecus pygerythrus,Cercopithecus sabeus,Cercopithecus tantalus,Chlorocebus cynosuros,Chlorocebus cynosurus,Chlorocebus pygerythrus,Green Monkey,Grivet Monkey,Lasiopyga weidholzi,Malbrouck,Malbrouck Monkey,Monkey, African Green,Monkey, Green,Monkey, Grivet,Monkey, Vervet,Savanah Monkey,Vervet Monkey,Savannah Monkey,African Green Monkey,Chlorocebus cynosuro,Green Monkey, African,Green Monkeys,Grivet Monkeys,Malbrouck Monkeys,Malbroucks,Monkey, Malbrouck,Monkey, Savanah,Monkey, Savannah,Savannah Monkeys,Vervet Monkeys
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D003600	Cytosol	Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.	Cytosols
D004167	Diphtheria Toxin	An ADP-ribosylating polypeptide produced by CORYNEBACTERIUM DIPHTHERIAE that causes the signs and symptoms of DIPHTHERIA. It can be broken into two unequal domains: the smaller, catalytic A domain is the lethal moiety and contains MONO(ADP-RIBOSE) TRANSFERASES which transfers ADP RIBOSE to PEPTIDE ELONGATION FACTOR 2 thereby inhibiting protein synthesis; and the larger B domain that is needed for entry into cells.	Corynebacterium Diphtheriae Toxin,Toxin, Corynebacterium Diphtheriae
D004705	Endocytosis	Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.	Endocytoses