Author response image 1. Partial recoating of previously uncoated CCVs was not robust enough to produce a significant difference in acidification assay.

(A) Electron micrographs of negatively stained sample after the vernight “recoating” treatment as detailed in Materials and methods. While coat formation sometimes occurs without the vesicle at its center, several vesicles surrounded by a new coat are clearly seen (indicated by a white arrow). Scale bar 200 nm. (B) Membrane potential of acidified vesicles after the overnight “recoating” treatment Error bars represent SD of 3 experimental replicates.