Endosome maturation in animal cells has been challenging to characterize by microscopy because the fluorescence patterns are complex and dynamic. This study uses acute ionophore treatment to generate enlarged early endosomes, whose behavior and maturation can then be readily tracked. The results offer new insights into several phenomena, including the regulation of endosomal acidification during the maturation process.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 and Reviewer #3 agreed to share their names with the authors.)