Prokaryotic 2-component signaling pathways for use as logic gates in mammalian cells

An isolated mammalian cell comprising at least one prokaryotic two-component signaling (TCS) pathway comprised of

• i. an activator protein A,
• ii. a response regulator (RR) protein B activated by said protein A, such activation leading to an activated RR protein B, and
• iii. an output gene C operably linked to a promoter,
• wherein transcription of the transcription apparatus in said isolated mammalian cell from said promoter is activated by activated RR protein B, and expression of output gene C defines at least a first state 0, which designates no transcription, and a second state 1, which designates detectable transcription, and
• wherein said activator protein A is a sensor histidine kinase comprising a histidine residue, said RR protein B is a transcriptional regulator comprising an aspartic acid residue, and activation of said RR protein B by said activator protein A is effected by transfer of a phosphate from said histidine residue to said aspartic acid residue.