An exotoxin, produced by Vibrio cholerae and Vibrio eltor, thats
leeds to the massive, watery diarrhea characteristic of cholera
infection.
The cholera toxin is a member of the AB family of toxins. The
function of the non-toxic B subunit is to assemble into a
ring-shaped, homologous pentamer and to adhere to mem-brane
receptors on the intestinal epithelial cell surface (GM1
gangliosides). The pathogenic effect stems from the A subunit. This
is split into two domains, an anchor domain A2 and a toxic domain
A1. The anchor domain binds the toxic A1 domain to the B subunit.
Through a series of further intermediate activation steps, the A1
domain ultimately causes a massive secretion of chloride ions in
the gut lumen, causing diarrhoea. It follows that the A1 subunit is
toxic, but the B subunit is non-toxic.
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