Cholera toxin (CT) consists of a pentameric B subunit that binds to specific cell surface receptors identified as ganglioside GM1 and an A subunit that activates adenylylcyclase. The A subunit consists of A1 and A2 peptides linked by a disulfide bond; A2 acts to connect A to B, whereas A1 is an ADP-ribosyltransferase that modifies the alpha subunit of the stimulatory G protein (Gs). How the tox...

.....................................................................................................42 Introduction ................................................................................................42 Materials and Methods................................................................................44 Cell culture and transfections .................................................

Evidence is presented that endocytosis is involved in the transport to the cytosol of the cytotoxin from Shigella dysenteriae 1, Shiga toxin, which acts by removal of a single adenine residue in 28-S ribosomal RNA. Inhibition of endocytosis by ATP depletion of the cells prevented toxin uptake. Exposure of HeLa $3 and Vero cells to toxin at low extracellular pH, where translocation to the cytoso...

Enterohemorrhagic Escherichia coli (EHEC) causes hemorrhagic colitis in humans and, in a subgroup of infected subjects, a more serious condition called hemolytic-uremic syndrome (HUS). These conditions arise because EHEC produces two antigenically distinct forms of Shiga toxin (Stx), called Stx1 and Stx2. Despite this, the production of Stx2 by virtually all EHEC serotypes and the documented ro...

A/B toxins such as cholera toxin, Pseudomonas exotoxin and killer toxin K28 contain a KDEL-like amino acid motif at one of their subunits which ensures retrograde toxin transport through the secretory pathway of a target cell. As key step in host cell invasion, each toxin binds to distinct plasma membrane receptors that are utilized for cell entry. Despite intensive efforts, some of these recep...

It has previously been shown that the B subunit of cholera toxin, which binds solely to the plasma membrane ganglioside GM1, stimulates the proliferation of rat thymic lymphocytes (Spiegel, S., P. H. Fishman, and R. J. Weber, 1985, Science [Wash. DC], 230:1285-1287). The purpose of this study was to identify which transmembrane signaling system(s) are activated by the B subunit of cholera toxin...

We compared the BD MAX enteric bacterial panel (EBP) to culture for the detection of Salmonella, Shigella, Campylobacter, and Shiga toxin-producing enterohemorrhagic Escherichia coli (EHEC) O157 in seeded stool samples. The EBP panel demonstrated superior sensitivity and reliably detected Salmonella, EHEC O157, Shigella, and Campylobacter at concentrations 1- to 2-log10 lower than those needed ...

Binding of cholera toxin to Giardia lamblia was demonstrated by two slightly different methods: an immunofluorescence technique using antibody to cholera toxin and anti-rabbit immunoglobulin G conjugated to fluorescein isothiocyanate, and a one-step fluorescence method in which G. lamblia was incubated with the B subunit of cholera toxin conjugated to fluorescein isothiocyanate.

Cholera toxin, or peptide A1 from the toxin, activates adenylate cyclase solubilized from rat liver with Lubrol PX, provided that cell sap, NAD+, ATP and thiol-group-containing compounds are present. The activation is abolished by antisera to whole toxin, but not to subunit B.