Abstract: The present invention relates to a method for producing a panel of cells (i.e. a cell library) expressing various different mutant variants of a protein of interest, wherein only one of said mutant variants is expressed per cell from a single gene copy. The present invention also relates to a method or cell library for identifying a mutant variant of a protein of interest having a different or modified biological activity as compared to the corresponding wild-type protein of interest. According to the present invention the identified mutant variant of a protein of interest may be applied for white biotechnology.

Abstract: The present invention relates to a method for producing a panel of cells (i.e. a cell library) expressing various different mutant variants of a protein of interest, wherein only one of said mutant variants is expressed per cell from a single gene copy. The present invention also relates to a method or cell library for identifying a mutant variant of a protein of interest having a different or modified biological activity as compared to the corresponding wild-type protein of interest. According to the present invention the identified mutant variant of a protein of interest may be applied for white biotechnology.

Abstract: The present invention relates to genetically encoded calcium sensors comprising fluorescent proteins and troponin C as calcium-binding moiety. More specifically, the invention provides a polypeptide comprising a donor moiety for fluorescence resonance energy transfer (FRET), at least two calcium binding moieties derived from the C-terminal domain of troponin C, and an acceptor moiety for FRET. Also, the invention provides nucleic acid molecules, expression vectors, host cells, and transgenic animals. In addition, methods for detecting a change in Ca2+ concentration or Mg2+ concentration, as well as uses of the polypeptides for preparing diagnostic compositions for the detection of changes in the Ca2+-concentration or Mg2+-concentration are provided.

Abstract: The present invention relates to novel types of cellular calcium probes that are based on Troponin C and two chromophors suitable for FRET (fluorescence resonance energy transfer). The Troponin C-based calcium sensors of the invention function in diverse subcellular environments, for example even when tethered to a cellular membrane. The invention further provides nucleic acid constructs encoding the calcium probes of the invention, expression constructs, host cells and transgenic animals. Furthermore, methods for the detection of changes of local calcium concentrations and for detecting the binding of a small molecule to fragments of Troponin C are provided.