Growth phase-dependent transcription of emrKY, a homolog of multidrug efflux emrAB genes of Escherichia coli, is induced by tetracycline.

The genes emrK and emrY were found between genes dsdA and evgA at 51 min on the Escherichia coli chromosome and form an operon. EmrK and EmrY are 50.4 and 63.