Yellow-green fluorescent, potassium (K⁺) indicator, membrane permeable. Higher K⁺ affinity than IPG-1 and IPG-2, with improved selectivity for K⁺ over sodium.
ION Potassium Green – 4 (IPG-4) is a yellow-green fluorescent, potassium (K⁺) indicator with Ex/Em: 525 nm/545 nm and a high-selectivity for potassium over other monovalent cations. IPG-4 has the highest affinity (Kd = 7 mM) among IPG analogues – IPG-2 (Kd = 18 mM) and IPG-1 (Kd = 50 mM), and is useful for measuring changes in intracellular or extracellular potassium concentrations.