FM dyes are a class of fluorescent molecules that has found important use in studying the vesicle recycling process. By virtue of a chemical structure, these molecules can insert themselves into the outer leaflet of phospholipid bilayer membranes. After membrane insertion, they are internalized into the cell via endocytosed vesicles, and released when these vesicles recycle back to the membrane. Since, these dyes fluoresce strongly in the hydrophobic environment within membranes and weakly in the extracellular compartment, FM fluorescence levels can be used to track vesicular activity throughout the recycling process.

This video provides an introduction to the use of FM dyes in experiments aimed to examine vesicle recycling. We first review the biochemistry of FM dyes and how their properties permit their use in these experiments. We then go through a general protocol for using FM dyes in such studies, and finally, discuss some recent research that makes use of these unique molecules.