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Biomedical subjects

W E van Heyningen

Publications and source records attributed to W E van Heyningen.

8 recordsLinked to original sources
PubMed1979

Unmasking of actual and potential receptor sites for cholera toxin in intestinal mucosal homogenates.

Endongenous and exogenous sialidases appear to unmask sialidase-stable and sialidase-labile gangliosides in intestinal mucosal homogenates by attacking glycoproteins. Exogenous (but not endogenous) sialidase then converts sialidase-labile gangliosides into the cholera toxin-binding, sialidase-stable ganglioside GM1 (galactosyl-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide). Since Vibrio cholerae produces sialidase, these observations may be relevant to the course of cholera.

Animals↗
PubMed1976

Aspects of the interaction of Vibrio cholerae toxin with the pigeon red cell membrane.

The ganglioside galactosy-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide (GM1) is readily accumulated in pigeon red cell membranes soaked with [3H]GM1 (1-100 mug/ml) at 37 C for 30 min. This treatment enhances the activation of adenyl cyclase by the toxin of Vibrio cholerae. An attempt was made at correlation of the amount of incorporated GM1 with the increased binding of toxin and activation of adenyl cyclase. Cells with less than 2 mug of incorporated GM1 per 4 X 10(9) cells bind 5-10 mug more toxin than do untreated cells, which bind 0.25 mug per 4 X 10(9) cells. Cells with more than 2 mug of GM1 bound (per 4 X 10(9) CELls) which has been incorporated from micellar solutions of GM1 (greater than 20 mug/ml), do not bind any more extra toxin. In untreated cells, 0.1 mug of toxin is involved in the activation of adenyl cyclase. In GM1-treated cells 0.25-0.5 mug of toxin is involved, although at least 5 mug of toxin is bound. It is concluded that 90% of the extra toxin-binding sites on the GM1-treated cell are nonproductive.

Adenylyl Cyclases↗
PubMed1975

Evidence for the complex nature of the ganglioside receptor for cholera toxin.

Choleragenoid binds more slowly and less strongly than cholera toxin to intestinal mucosal cells, and even less strongly to free ganglioside in solution. However, binding to ganglioside is greatly enhanced when the ganglioside is in the form of an insoluble complex with cerebroside. These findings suggest that both the binding and the active components of the toxin molecule may be necessary for optimal binding of the toxin to the intact cell, and that the ganglioside in the cell receptor is in a complex form. Choleragenoid only partially blocks the action of the toxin on ruptured cells. This observation indicates that, while binding to a membrane receptor is necessary for the action of the toxin on the whole cell, it is possible to activate adenyl cyclase in a perforated cell by a process apparently independent of membrane binding; however, this activation may be possible only if the toxin preparation contains the active component dissociated from choleragenoid.

Adenosine Triphosphate↗