Figure 1: (a) Structure of biotin-pendant Phos-tag ligand (BTL-104) and scheme for reversible capture of a phosphomonoester dianion (R-OPO32–) by the Zn(II) complex of Phos-tag Biotin. (b) Schematic representation of ECL detection of phosphoproteins on a protein-blotting membrane by using Phostag Biotin. The membrane was probed by using the complex of Phos-tag Biotin with HRP–SA, and then the Phos-tag-bound phosphoproteins were detected by an ECL system.