Botulinum Toxin Belongs to a Group of Toxins Called A-B

Question

Botulinum toxin belongs to a group of toxins called A-B toxins.What does the term "A-B" refer to?
A)Their antigen-binding properties.
B)Their antibody-binding toxins.
C)Their enzymatically active subunit and cell binding subunit.
D)Their action on the brain.
E)Their activation of B-cells.

Accepted Answer

The term "A-B" refers to the two subunits of these toxins. The A subunit is the enzymatically active subunit that causes toxicity, while the B subunit is responsible for binding to specific receptors on the surface of target cells. A-B toxins are characterized by their ability to enter the host cell by receptor-mediated endocytosis. Once inside the cell, the toxin's A subunit separates from the B subunit and brings about its toxic effects. Botulinum toxin, for example, cleaves proteins involved in neurotransmitter release, resulting in muscle paralysis.