Endosidin9 (ES9) is a potent inhibitor of clathrin-mediated endocytosis (CME) in Arabidopsis thaliana, HeLa cells and Drosophila neurons. It binds directly to N-terminal domain of clathrin heavy chain. Also, Endosidin9 is a mitochondrial uncoupler that displays protonophore activities leading to cytoplasm acidification.