UAS regulatory sequences drive expression of two coding regions separated by a 2A peptide sequence that are designed to be used to report neuromodulator release in vivo using the 'Tango' system (PMID:18165312). The upstream coding region encodes a tethered transcription factor which is composed of the Oamb receptor fused via a Tag:CS(TEVp) cleavage site to a lexA::UnkAD driver (the driver is tagged with the Tag:HA epitope) (this coding region is represented in FlyBase by the OambUAS.Tango allele). The downstream coding region consists of Arr1 fused to the TEVp protease (this coding region is represented in FlyBase by the Arr1::TEV\NIaUAS.Tango allele). Upon activation of the Oamb receptor by its ligand, the Arr1 ::TEVp protein is recruited, resulting in cleavage at the Tag:CS(TEVp) site. This allows the Tag:HA-tagged lexA::UnkAD driver to translocate to the nucleus, where it can drive expression of a reporter that is controlled by lexAop regulatory sequences.
The Tango system (first described in Barnea et al., 2008 - PMID:18165312 ) is used to report endogenous neuromodulator release in vivo with anatomic specificity. The presence of a 2A peptide sequence allows dicistronic expression of two coding regions within the same construct by forcing the ribosome to skip from a glycine to a proline without forming a peptide bond, resulting in stochiometric production of two proteins. These proteins are: 1) a neuromodulator receptor tethered to T:Ivir\HA1 tagged Ecol\lexA via a TEV protease cleavage site (T:Zzzz\TEV.CS) and 2) a Arr1-Zzzz\NIa fusion protein. On binding of the neuromodulator to the Ecol\lexA-T:Ivir\HA1 bound receptor, the Arr1-Zzzz\NIa fusion protein cleaves Ecol\lexA T:Ivir\HA1 from the receptor, allowing it to translocate to the nucleus where it can drive expression of a Ecol\lexAop-driven reporter.
The P{UAS-Oamb-Tango} construct can be used as a reporter of octopamine release in vivo.