You have isolated a strain of cholera that does not induce the same symptoms in host organisms as
The wild-type pathogen. The toxin from wild-type cholera is known to cause diarrhea only after its 2 polypeptide subunits dissociate from each other. This dissociation occurs when the toxin enters an acid environment. You find that the strain you have isolated is not localized to a particular cellular location, which likely explains the lack of activity. In which of the following cellular locations are the wild-type toxin subunits most likely to dissociate from each other, thereby becoming active?
A) coated vesicle
B) cytosol
C) endosome
D) mitochondrial matrix
E) nucleus

Question

Quizplus · Accepted Answer

The wild-type cholera toxin becomes active in an acidic environment, which is characteristic of the endosome.  Endosomes are membrane-bound compartments inside cells. They are compartments of the endocytic membrane transport pathway from the plasma membrane to the lysosome. For example, when low-density lipoprotein (LDL) binds the LDL receptor, the complex is internalized and fused to the endosomal membranes. Because of the slightly acidic environment of the endosome, ligands, such as LDL, dissociate.

You Have Isolated a Strain of Cholera That Does Not