Ionomycin

Ionomycin is a calcium ionophore antibiotic produced by certain Streptomyces species. It functions by binding divalent calcium ions and shuttling them across biological membranes, increasing cytosolic Ca2+ concentrations in a dose-dependent manner. The compound is lipophilic and forms a Ca2+-ionophore complex that transports Ca2+ through lipid bilayers, effectively dissipating Ca2+ gradients across membranes.

In laboratory settings, ionomycin is used as a tool to raise intracellular calcium independently of receptor-mediated signaling. It is commonly employed with Ca2+-sensitive fluorescent dyes such as Fura-2 or Fluo-4 to study calcium signaling, and in immunology to activate lymphocytes in vitro. It is typically used at micromolar to low-micromolar concentrations, depending on cell type and assay. Solutions are usually prepared in DMSO and stored protected from light.

Safety and handling: Ionomycin is a potent bioactive compound and cytotoxic at higher concentrations; handle with appropriate PPE and dispose of as hazardous chemical. It is intended for research use only and not approved for therapeutic use.

Ionomycin belongs to a class of polyether ionophores that includes related compounds such as A23187 (calcimycin), monensin, and nigericin, which have differing ion selectivity and applications.