G418
G418 is an aminoglycoside antibiotic similar in structure to gentamicin. It is produced by the bacterium Micromonospora rhodorangea. G418 blocks polypeptide synthesis by inhibiting the elongation step in both prokaryotic and eukaryotic cells. In molecular biology, it is used as a selective agent to identify cells that have been successfully genetically modified using the neomycin resistance gene (Neo^R), which provides resistance to G418.
History[edit | edit source]
G418 was first isolated in the 1970s from the bacterium Micromonospora rhodorangea. It was initially used as an antibiotic in veterinary medicine, but its use in molecular biology research has since become more prevalent.
Mechanism of Action[edit | edit source]
G418 inhibits protein synthesis by binding to the ribosome, specifically the 30S ribosomal subunit, and causing misreading of the mRNA template. This results in the production of non-functional or toxic peptides, leading to cell death.
Use in Molecular Biology[edit | edit source]
In molecular biology, G418 is used as a selective agent to identify cells that have been successfully genetically modified. The neomycin resistance gene (Neo^R) is often included in the DNA construct that is introduced into the cells. This gene codes for an aminoglycoside phosphotransferase enzyme that can inactivate G418 by phosphorylation. Cells that have incorporated the Neo^R gene into their genome will be resistant to G418, while non-transformed cells will be sensitive to the antibiotic and will die.
Safety and Toxicity[edit | edit source]
Like other aminoglycoside antibiotics, G418 can be toxic to humans. It can cause damage to the kidneys and the auditory nerve, leading to nephrotoxicity and ototoxicity, respectively. Therefore, it should be handled with care in the laboratory.
See Also[edit | edit source]
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