Question

A drop in pH marks the maturation of endosomes and the conversion to lysosomes. Which of the following is likely responsible for this particular pH change?

1) the acid hydrolases
2) v-type proton pumps in the endosome membrane
3) soluble proteins in the endosome
4) lysosomal-directed tags on membrane proteins

Answer 1

V-type proton pumps in the endosome membrane are responsible for the drop in pH that marks the maturation of endosomes and the conversion to lysosomes.

Step-by-step explanation:

The drop in pH that marks the maturation of endosomes and the conversion to lysosomes is likely due to v-type proton pumps in the endosome membrane. These pumps actively transport protons into the endosome, making the interior more acidic. The acid hydrolases, soluble proteins, and lysosomal-directed tags on membrane proteins all play important roles in the function of lysosomes, but they are not primarily responsible for the pH change.