A light to show the way: A hydroxy group in mugineicacid (MA) that was not needed for FeIII complexation was used for the introduction of various labeling groups through propargylation and a click reaction. Labeled MA was incorporated as a phytosiderophore into Xenopus oocytes through the HvYS1 transporter, as determined by an electrophysiological assay and fluorescence microscopy (see picture). Cbz=carbobenzyloxy