Use and Mechanism of Geneticin(G418)

G418 (Geneticin) is an aminoglycoside antibiotic similar in structure to gentamicin B1. It is produced by Micromonospora rhodorangea.

Mechanism of action

G418 blocks polypeptide synthesis by inhibiting the elongation step in both prokaryotic and eukaryotic cells.Resistance to G418 is conferred by the neo gene from Tn5 encoding an aminoglycoside 3'-phosphotransferase, APT 3' II.G418 is an analog of neomycin sulfate, and has similar mechanism as neomycin. G418 is commonly used in laboratory research to select genetically engineered cells .

In general for bacteria and algae concentrations of 5 μg/mL or less are used, for mammalian cells concentrations of approximately 400 μg/mL are used for selection and 200 μg/mL for maintenance. However, optimal concentration for resistant clones selection in mammalian cells depends on the cell line used as well as on the plasmid carrying the resistance gene, therefore antibiotic titration should be done to find the best condition for every experimental system. Titration should be done using antibiotic concentrations ranging from 100 μg/mL up to 1400 μg/mL. Resistant clones selection could require from 1 to up to 3 weeks.

Use in cell biology

G418 is routinely used as a selective agent in cell culture set-ups. Researchers can link the neoR selective resistance gene with their vector. Then if the vector is successfully introduced into cells, the cells can become G418-resistant cells. After treating with G418, these vector(-) cells will die, while vector(+) cells will survive. This method can help researchers select vector(+) cells.