Tetracycline-Controlled Transcriptional Activation is a method of inducible
gene expression where
transcription is reversibly turned on or off in the presence of the
antibiotic tetracycline or one of its derivatives (e.g.
doxycycline). In nature, the P
tet promoter expresses TetR, the repressor, and TetA, the protein that pumps tetracycline antibiotic out of the cell.