Resistance to the antibiotic ampicillin
The ampR-gene exists naturally in various microorganisms. It is responsible for the synthesis of a certain enzyme (beta-lactamase) that neutralises the antibiotic ampicillin - a modified form of penicillin.
The ampR-gene is used as a genetic marker for the identification of genetically transformed plants and microorganisms.
In human medicine, ampicillin is used against certain infections. Many pathogens, however, have become resistant to ampicillin.