Ionomycin (SQ23377) is a Selective Calcium Ionophore and an Antibiotic

In the furnaces of the stars the elements evolved from hydrogen. When oxygen and neon captured successive α particles, the element calcium was born. Calcium ions (Ca2+) are some of the most versatile signalling molecules in cells. Cells invest much of their energy to effect changes in Ca2+ concentration. Ca2+ maintains a 20,000-fold gradient between intracellular (approximately 100 nM free) and extracellular (mM) concentrations. Ca2+ exhibits enormous versatility. On the one hand, it can control processes as diverse as fertilization, proliferation, development, learning and memory, contraction and secretion. On the other hand, Ca2+ can also result in cell death through both necrosis and apoptosis.

Antibiotics are medicines that fight bacterial infections in people and animals. They are a class of secondary metabolites. Some of them exhibit anti-bacterial, anti-fungal, anthelmintic, anti-tumor or immunosuppressive activities with a wealth of structural classes such as β-lactams, macrolide and polyether. Generally, they work by killing the bacteria or by making it hard for the bacteria to grow and multiply. However, antibiotics only treat certain bacterial infections, such as strep throat, urinary tract infections, and E. coli. And it do not work on viral infections. Currently, penicillin, cephalosporin, streptomycin and tetracycline are the most common antibiotics.

Ionomycin (SQ23377) is a potent, selective calcium ionophore and an antibiotic.


Ionomycin is an ionophore and an antibiotic that binds Ca2+ in a ratio 1:1. It is produced by the bacterium Streptomyces conglobatus. It binds also other divalent cations like magnesium and cadmium, but binds Ca2+ preferably. Ionomycin helps to activate the cell by increasing the calcium permeability of the cell membrane, thereby allowing extracellular calcium to flow into the cell. Therefore, it can be used as a research tool to understand Ca2+ transport across biological membranes. Ionomycin can also stimulate cells to produce some cytokines, such as interferon, perforin, IL-2 and IL-4 by using it in combination with PMA. These cytokines play an important role in the inflammatory response.

In conclusion, Ionomycin is a potent, selective calcium ionophore and an antibiotic produced by Streptomyces conglobatus.

Berridge MJ, et, al. Nat Rev Mol Cell Biol. 2000 Oct;1(1):11-21.