@article{DeMicheleAstLoqueetal.2013,
  author    = {De Michele, Roberto and Ast, Cindy and Loque, Dominique and Ho, Cheng-Hsun and Andrade, Susana L. A. and Lanquar, Viviane and Grossmann, Guido and Gehne, Soeren and Kumke, Michael Uwe and Frommer, Wolf B.},
  title     = {Fluorescent sensors reporting the activity of ammonium transceptors in live cells},
  series = {ELIFE},
  volume    = {2},
  journal   = {ELIFE},
  number    = {3},
  publisher = {ELIFE SCIENCES PUBLICATIONS LTD},
  address   = {CAMBRIDGE},
  issn      = {2050-084X},
  doi       = {10.7554/eLife.00800},
  pages     = {22},
  year      = {2013},
  abstract  = {Ammonium serves as key nitrogen source and metabolic intermediate, yet excess causes toxicity. Ammonium uptake is mediated by ammonium transporters, whose regulation is poorly understood. While transport can easily be characterized in heterologous systems, measuring transporter activity in vivo remains challenging. Here we developed a simple assay for monitoring activity in vivo by inserting circularly-permutated GFP into conformation-sensitive positions of two plant and one yeast ammonium transceptors (\’AmTrac and \’MepTrac\’). Addition of ammonium to yeast cells expressing the sensors triggered concentration dependent fluorescence intensity (FI) changes that strictly correlated with the activity of the transporter. Fluorescence-based activity sensors present a novel technology for monitoring the interaction of the transporters with their substrates, the activity of transporters and their regulation in vivo, which is particularly valuable in the context of analytes for which no radiotracers exist, as well as for cell-specific and subcellular transport processes that are otherwise difficult to track.},
  language  = {en}
}
@article{KienzlerFlehrKrameretal.2011,
  author    = {Kienzler, Andrea and Flehr, Roman and Kramer, Rolf A. and Gehne, Soeren and Kumke, Michael Uwe and Bannwarth, Willi},
  title     = {Novel Three-Color FRET Tool Box for Advanced Protein and DNA Analysis},
  series = {Bioconjugate chemistry},
  volume    = {22},
  journal   = {Bioconjugate chemistry},
  number    = {9},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1043-1802},
  doi       = {10.1021/bc2002659},
  pages     = {1852 -- 1863},
  year      = {2011},
  abstract  = {We report on a new three-color FRET system which we were able to verify in peptides as well as in synthetic DNA. All three chromophores could be introduced by a building block approach avoiding postsynthetic labeling. Additional features are robustness, matching spectroscopic properties, high-energy transfer, and sensitivity. The system was investigated in detail on a set of peptides as well as an array of tailored oligonucleotides. The detailed analysis of the experimental data and comparison with theoretical considerations were in excellent agreement. It is shown that in the case of polypeptides specific interaction with the fluorescence probes has to be considered. In contrast with DNA, the fluorescence probes did not show any indications of such interactions. The novel three-color FRET toolbox revealed the potential for applications studying fundamental processes of three interacting molecules in life science applications.},
  language  = {en}
}