Abstract: Method for the detection in homogeneous medium of a post-translational modification of a proteinaceous substrate catalyzed by a cell enzyme, characterized in that the post-translational modification reaction takes place in intact living cells, in that these cells comprise a heterologous expression vector coding for a fusion protein comprising the proteinaceous substrate and a first coupling domain and in that it comprises the following stages: (i) Incubation of the cells in the presence or in the absence of a compound to be tested capable of modulating the activity of said enzyme, (ii) Addition to the reaction medium of a first fluorescent compound member of a first pair of FRET partners covalently bonded to a coupling agent capable of binding specifically to the first coupling domain present on the proteinaceous substrate, (iii) Addition to the reaction medium of a second fluorescent compound member of this first pair of FRET partners, and covalently bonded to a binding domain specific to the site of the

Abstract: Method for the detection in homogeneous medium of a post-translational modification of a protein substrate catalyzed by a cell enzyme, characterized in that the post-translational modification reaction takes place in intact living cells, in that these cells comprise a heterologous expression vector coding for a fusion protein comprising the protein substrate and a first coupling domain and in that it comprises the following stages: (v) Incubation of the cells in the presence or in the absence of a compound to be tested capable of modulating the activity of said enzyme, (vi) Addition to the reaction medium of a first fluorescent compound member of a first pair of FRET partners covalently bonded to a coupling agent capable of binding specifically to the first coupling domain present on the protein substrate, (vii) Addition to the reaction medium of a second fluorescent compound member of this first pair of FRET partners, and covalently bonded to a binding domain specific to the site of the protein substrate hav

Abstract: The invention relates to 3-D structures of a polypeptide, whereby, in the 3-D structure, the polypeptide contains at least one amino acid sequence of a TPR-structure motif from a Hop protein, or a derivative thereof, The invention further relates to crystals, comprising at least one polypeptide in their asymmetric unit and, optionally, at least one further compound, whereby the polypeptide adopts the above 3D-structure in the crystal. Furthermore, methods for the production of such crystals and compounds, having the property of binding, as ligands, to structural regions of a Hop protein are disclosed. Additionally, a method for the identification of inhibitors is disclosed, whereby ligands with inhibitor functions for the interaction of a Hop protein with at least one chaperone protein are obtained. Such inhibitors are useful for the treatment of tumour disease states, immunosupression, GVDH, or the treatment of viral infections.