Chemical dissection of endosomal pathways.

Membrane trafficking and associated signal transduction pathways are critical for plant development and responses to environment. These transduction pathways, including those for brassinosteroids and auxins, require endocytosis to endosomes and recycling back to the plasma membrane. A major challenge toward understanding these processes and their biological roles has been the highly dynamic nature of endomembrane trafficking. To effectively study endocytosis and recycling, which occur in a time frame of minutes, bioactive chemicals provide a powerful and exacting tool. Pharmacological inhibitors such as Brefeldin A (BFA) and the newly identified Endosidin 1 (ES1) have been used to define endosome compartments. ES1 is a clear example of the ability of chemicals to dissect even distinct subpopulations of endosomes involved in trafficking and signal transduction. The ability to characterize and dissect such highly dynamic pathways in a temporal and spatial manner is possible only using pharmacological reagents which can act rapidly and reversibly.